| name | powerlanguage-syntax |
| description | Use when reading or writing PowerLanguage code — declarations, data types, begin/end rules, control flow, bar references (Close[N]), Value/Condition built-ins, trade-state variables (MarketPosition, EntryPrice), and gotchas including "syntax error, unexpected X" / "Wrong syntax of X" from keywords used as RHS values, MarketPosition(N) being position history (not bar offset), and bars labeled by close time. |
PowerLanguage Syntax
Declarations
Every script starts with declarations. Order matters: Inputs: comes before Variables: (or its aliases Vars:, Var:); both come before code.
Inputs:
Length(20),
Threshold(0.0);
Variables:
avgVal(0),
triggered(False);
Arrays:
buffer[10](0);
- Inputs — parameters exposed in the script's Format window. Each gets a default value in parentheses. Read-only inside the script.
- Variables / Vars / Var — script state. Each gets an initial value. Persist across bars within the same chart.
- Arrays — fixed-size collections.
[size] is the index of the last element (zero-based by default), (initial) initializes every slot.
Pre-declared default variables. PowerLanguage ships with numbered built-ins that don't need a Variables: declaration:
| Name | Type | Documented range | Notes |
|---|
Value0 … Value99 | numeric | 100 (official docs) | MC 15 compiler empirically accepts much higher indices — Value10000 compile-verified — but anything past Value99 is undocumented |
Condition0 … Condition99 | truefalse | 100 (official docs) | Indices past Condition99 are unverified — do not emit them in generated code |
Use them directly: Value1 = Average(Close, 14);, If Condition1 Then Buy ...;. No declaration line required (declaring one just shadows the built-in with an identical local). These are handy for quick scratch values when you don't want to bother naming a variable. For generated code, stay within 0–99 — declare named variables if you need more.
Data types
PowerLanguage is loosely typed but each value is one of:
| Type | What it is | Literal examples |
|---|
| Numeric | Floating-point number | 0, 1.5, -3.14 |
| String | Text | "hello", "LE" |
| TrueFalse (bool) | Boolean | True, False |
Type is inferred from initial value in Variables: / Inputs: declarations.
The begin … end rule and semicolons
begin opens a block; end closes it. Every end gets a semicolon EXCEPT when followed by else.
// (pseudocode — real scripts need Variables declarations for all names)
If condition Then Begin
statement1;
statement2;
End // NO semicolon — else follows
Else Begin
statement3;
End; // semicolon — outer statement boundary
Forgetting a semicolon on a terminal End is the most common compile error new PowerLanguage users hit. The rule is mechanical: if the next token is Else, no semicolon; otherwise yes.
Control flow
// (pseudocode forms — declare all variables in real scripts)
If x > 0 Then Begin ... End;
If x > 0 Then ... Else If x = 0 Then ... Else ... ;
Variables: idx(0), runTotal(0); // loop counter + accumulator must be declared
For idx = 1 To 10 Begin
runTotal = runTotal + idx;
End;
While condition Begin ... End;
Switch (n) Begin
Case 0: Value1 = Value1; // no-op — empty case body is a compile error
Case 1: ... ;
Case 2: ... ;
Default: ... ;
End;
Every Case body must have at least one statement. An empty case (even with only a comment) is a compile error. Use Value1 = Value1; as a no-op if the case should do nothing.
For / While loop counters must be declared as Variables. PowerLanguage does not auto-declare loop counters. Using an undeclared name gives "Invalid type operation."
Bar references
Close is the close price of the current bar; Close[1] is the close one bar ago; Close[N] is N bars ago. Same indexing for Open, High, Low, Volume, OpenInterest.
| Built-in | Meaning |
|---|
Close, Open, High, Low | OHLC of current bar |
Volume | Volume of current bar |
OpenInterest | OI of current bar (futures/options) |
Date | Bar date as YYYMMDD integer, format (YYYY-1900)*10000 + MM*100 + DD — 7 digits for years 2000–2099 (e.g. 1260610 = 2026-06-10), 6 digits for 1900–1999 (e.g. 990115 = 1999-01-15) |
Time | Bar close time as HHMM integer — see gotcha below |
BarNumber | Sequential count, same as CurrentBar |
Operators
- Arithmetic:
+, -, *, /
- Comparison:
=, <>, >, <, >=, <=
- Logical:
and, or, not (lowercase; and is a keyword, not &&)
Comments
- Line comment:
// up to end of line
- Block comment:
{ braces — can span multiple lines }
The { … } block-comment form is also how PowerLanguage code authors traditionally write file headers.
Built-in trade-state variables (Signal scripts)
Inside a Signal script, these are always available — no declaration needed:
| Variable | Meaning |
|---|
MarketPosition | 1 if long, -1 if short, 0 if flat. Optional (N) = Nth-ago position — see gotcha below |
CurrentContracts | Absolute size of current position |
EntryPrice | Average fill price of current position. Optional (N) = Nth-ago position |
BarsSinceEntry | Bars since current position was entered. Optional (N) = Nth-ago position |
BarsSinceExit(N) | Bars since the Nth-most-recent exit |
Order syntax (high-level recap)
Buy ("LE") 1 Contract Next Bar at Market;
Sell ("LX") 1 Contract Next Bar at Market;
SellShort ("SE") 1 Contract Next Bar at Market;
BuyToCover ("SX") 1 Contract Next Bar at Market;
Quantities use Contract / Contracts (futures, FX) or Share / Shares (equities). The price-placement keyword (Market, Limit, Stop, This Bar on Close) determines when the fill happens. See powerlanguage-keywords-reference for each order keyword's full signature.
Common built-in functions
MultiCharts ships with hundreds of pre-built Functions (.elf and .pla files) that are NOT in the keyword reference. These are the most commonly used ones — get the signatures right or you'll get compile errors.
Moving averages and smoothing
| Function | Signature | Returns |
|---|
Average | Average(Price, Length) | numeric |
XAverage | XAverage(Price, Length) | numeric (exponential MA) |
AverageFC | AverageFC(Price, Length) | numeric (fast calculation) |
WAverage | WAverage(Price, Length) | numeric (weighted MA) |
AdaptiveMovAvg | AdaptiveMovAvg(Price, EffRatioLen, FastAvgLen, SlowAvgLen) | numeric (Kaufman AMA) |
MidPoint | MidPoint(Price, Length) | numeric |
TriAverage | TriAverage(Price, Length) | numeric (triangular MA; double-smoothed SMA) |
Oscillators and indicators
| Function | Signature | Returns |
|---|
RSI | RSI(Price, Length) | numeric (0–100) |
Stochastic | Stochastic(PriceH, PriceL, PriceC, StochLen, SmoothLen1, SmoothLen2, SmoothType, oFastK, oFastD, oSlowK, oSlowD) | numeric (1=ok, -1=error); populates 4 ref vars |
BollingerBand | BollingerBand(Price, Length, NumDevs) | numeric (+NumDevs for upper, -NumDevs for lower) |
MACD | MACD(Price, FastLen, SlowLen) | numeric |
KeltnerChannel | KeltnerChannel(Price, Length, NumATRs) | numeric |
CCI | CCI(Length) | numeric |
ADX | ADX(Length) | numeric |
DMIPlus | DMIPlus(Length) | numeric |
DMIMinus | DMIMinus(Length) | numeric |
Momentum | Momentum(Price, Length) | numeric |
RateOfChange | RateOfChange(Price, Length) | numeric |
PercentR | PercentR(Length) | numeric (Williams %R) |
MoneyFlow | MoneyFlow(Length) | numeric |
Parabolic | Parabolic(AfStep) | numeric (Parabolic SAR) |
Volatility | Volatility(Length) | numeric |
UltimateOscillator | UltimateOscillator(Len1, Len2, Len3) | numeric |
ChaikinOsc | ChaikinOsc(FastLen, SlowLen, SmoothType) | numeric |
PriceOscillator | PriceOscillator(Price, FastLen, SlowLen) | numeric |
TSI | TSI(Price, LongLength, ShortLength) | numeric (True Strength Index; double-smoothed momentum, range roughly −100 to +100) |
ADXR | ADXR(Length) | numeric (ADX Rating; average of current ADX and ADX N bars ago) |
ADXCustom | ADXCustom(PriceH, PriceL, PriceC, Length) | numeric (ADX with custom H/L/C) |
DMI | DMI(Length) | numeric (Directional Movement Index) |
DMIPlusCustom | DMIPlusCustom(PriceH, PriceL, PriceC, Length) | numeric (+DI with custom H/L/C) |
DMIMinusCustom | DMIMinusCustom(PriceH, PriceL, PriceC, Length) | numeric (−DI with custom H/L/C) |
ParabolicCustom | ParabolicCustom(AfStep, AfLimit) | numeric (Parabolic SAR with custom acceleration limit) |
TRIX | TRIX(Price, Length) | numeric (triple EMA rate-of-change) |
MassIndex | MassIndex(SmoothingLength, SummationLength) | numeric (signals reversal when crossing 27) |
EaseOfMovement | EaseOfMovement | numeric (no args; volume-weighted price movement) |
SwingIndex | SwingIndex | numeric (no args; Wilder's swing index, −100 to +100) |
AccumSwingIndex | AccumSwingIndex | numeric (no args; cumulative running total of SwingIndex) |
Detrend | Detrend(Price, Length) | numeric (detrended price; deviation from offset average) |
PercentChange | PercentChange(Price, Length) | numeric (percent change vs N bars ago) |
UlcerIndex | UlcerIndex(Price, Length) | numeric (downside volatility / drawdown stress) |
"No Price parameter" gotcha: These functions take no Price parameter — passing Close as the first arg is a compile error:
- Length-only:
CCI, ADX, ADXR, DMI, DMIPlus, DMIMinus, AvgTrueRange, PercentR, MoneyFlow, Volatility, RSquared, AccumDist — call as ADX(14), not ADX(Close, 14).
- Multi-length (no Price):
UltimateOscillator(Len1, Len2, Len3), ChaikinOsc(FastLen, SlowLen, SmoothType), MassIndex(SmoothLen, SumLen) — all parameters are lengths/types, not prices.
- Single non-length:
Parabolic(AfStep) — takes only an acceleration factor step, e.g. Parabolic(0.02).
- No arguments:
EaseOfMovement, SwingIndex, AccumSwingIndex, OBV, PriceVolTrend, LWAccDis — use current bar OHLCV internally.
Stochastic gotcha: It takes 11 parameters, not 3. The last 4 are output ref variables — you must declare Variables for them. The return value is just a status code (1 or -1), not the stochastic value itself. Typical usage:
Variables: fastK(0), fastD(0), slowK(0), slowD(0);
Value1 = Stochastic(High, Low, Close, 14, 3, 3, 1, fastK, fastD, slowK, slowD);
// Use slowK and slowD for signals
Stochastic helper functions
These are convenience wrappers around the full Stochastic function. The default variants use the current bar's High, Low, Close; the Custom variants accept explicit price inputs.
| Function | Signature | Returns |
|---|
FastK | FastK(StochLength) | numeric (raw Fast %K using default H/L/C) |
FastD | FastD(StochLength) | numeric (smoothed Fast %D using default H/L/C) |
SlowK | SlowK(StochLength) | numeric (Slow %K using default H/L/C) |
SlowD | SlowD(StochLength) | numeric (Slow %D using default H/L/C) |
FastKCustom | FastKCustom(PriceH, PriceL, PriceC, StochLength) | numeric (raw Fast %K with custom prices) |
FastDCustom | FastDCustom(PriceH, PriceL, PriceC, StochLength) | numeric (smoothed Fast %D with custom prices) |
SlowKCustom | SlowKCustom(PriceH, PriceL, PriceC, StochLength) | numeric (Slow %K with custom prices) |
SlowDCustom | SlowDCustom(PriceH, PriceL, PriceC, StochLength) | numeric (Slow %D with custom prices) |
StochasticExp | StochasticExp(PriceH, PriceL, PriceC, StochLength, SmoothLen1, SmoothLen2, oFastD, oSlowD) | numeric (returns Fast %K); uses EMA smoothing, populates 2 ref vars |
Multi-output functions
These functions populate output ref variables — you must declare Variables for each output parameter.
| Function | Signature | Returns |
|---|
DirMovement | DirMovement(H, L, C, Length, oDMIp, oDMIm, oADX, oDIp, oDIm, oADXr) | numeric; populates 6 ref vars |
Extremes | Extremes(Price, Length, ExtrType, oExtUp, oExtDn) | numeric; populates 2 ref vars |
ParabolicSAR | ParabolicSAR(AfStep, AfLimit, oParCl, oParOp, oPosition, oTransition) | numeric; populates 4 ref vars (close/open SAR, position direction, transition flag) |
LinearReg | LinearReg(Price, Length, TgtBar, oSlope, oAngle, oIntercept, oValueRaw) | numeric; populates 4 ref vars |
Volatility and range
| Function | Signature | Returns |
|---|
AvgTrueRange | AvgTrueRange(Length) | numeric |
TrueRange | TrueRange | numeric (no args) |
StandardDev | StandardDev(Price, Length, DataType) | numeric (DataType: 1=population, 2=sample) |
TrueHigh | TrueHigh | numeric (no args) |
TrueLow | TrueLow | numeric (no args) |
Range | Range | numeric (no args; High - Low) |
TrueRangeCustom | TrueRangeCustom(HPrice, LPrice, CPrice) | numeric (true range with custom H/L/C) |
VolatilityStdDev | VolatilityStdDev(NumDays) | numeric (annualized historical volatility: stdev of log returns) |
StandardDevAnnual | StandardDevAnnual(Price, Length, DataType) | numeric (annualized standard deviation) |
Price extremes and Nth
| Function | Signature | Returns |
|---|
Highest | Highest(Price, Length) | numeric |
Lowest | Lowest(Price, Length) | numeric |
HighestBar | HighestBar(Price, Length) | numeric (bars ago) |
LowestBar | LowestBar(Price, Length) | numeric (bars ago) |
NthHighest | NthHighest(Nth, Price, Length) | numeric |
NthLowest | NthLowest(Nth, Price, Length) | numeric |
NthHighestBar | NthHighestBar(Nth, Price, Length) | numeric (bars ago) |
NthLowestBar | NthLowestBar(Nth, Price, Length) | numeric (bars ago) |
HighestFC | HighestFC(Price, Length) | numeric (fast calculation Highest) |
LowestFC | LowestFC(Price, Length) | numeric (fast calculation Lowest) |
Swing detection
| Function | Signature | Returns |
|---|
SwingHigh | SwingHigh(Occurrence, Price, Strength, Length) | numeric (price at swing, or -1 if none) |
SwingLow | SwingLow(Occurrence, Price, Strength, Length) | numeric (price at swing, or -1 if none) |
SwingHighBar | SwingHighBar(Occurrence, Price, Strength, Length) | numeric (bars ago) |
SwingLowBar | SwingLowBar(Occurrence, Price, Strength, Length) | numeric (bars ago) |
Pivot with variable strength
Like SwingHigh/Low but with independent left and right strength parameters.
| Function | Signature | Returns |
|---|
PivotHighVS | PivotHighVS(Instance, Price, LeftStrength, RightStrength, Length) | numeric (price at pivot, or -1 if none) |
PivotLowVS | PivotLowVS(Instance, Price, LeftStrength, RightStrength, Length) | numeric (price at pivot, or -1 if none) |
PivotHighVSBar | PivotHighVSBar(Instance, Price, LeftStrength, RightStrength, Length) | numeric (bars ago) |
PivotLowVSBar | PivotLowVSBar(Instance, Price, LeftStrength, RightStrength, Length) | numeric (bars ago) |
Divergence detection
| Function | Signature | Returns |
|---|
Divergence | Divergence(Price1, Price2, Strength, Length, HiLo) | numeric (1 if divergence found; HiLo: -1=bullish, 1=bearish) |
Aggregation and linear regression
| Function | Signature | Returns |
|---|
Summation | Summation(Price, Length) | numeric |
Cum | Cum(Price) | numeric (cumulative sum from bar 1) |
LinearRegValue | LinearRegValue(Price, Length, Offset) | numeric |
LinearRegAngle | LinearRegAngle(Price, Length) | numeric |
LinearRegSlope | LinearRegSlope(Price, Length) | numeric |
Correlation | Correlation(Price1, Price2, Length) | numeric |
RSquared | RSquared(Length) | numeric |
StdError | StdError(Price, Length) | numeric |
Median | Median(Price, Length) | numeric |
TimeSeriesForecast | TimeSeriesForecast(Price, Length) | numeric (projected regression value) |
| SummationFC | SummationFC(Price, Length) | numeric (fast calculation Summation) |
Date/Time conversion
| Function | Signature | Returns |
|---|
ELDate | ELDate(Month, Day, Year) | numeric (EL date format) |
MinutesToTime | MinutesToTime(Minutes) | numeric (HHMM) |
TimeToMinutes | TimeToMinutes(Time) | numeric (total minutes) |
Multi-period OHLC reference
Access daily, weekly, monthly, or yearly OHLC from any intraday chart. PeriodsAgo = 0 is the current period.
| Function | Signature | Returns |
|---|
OpenD | OpenD(PeriodsAgo) | numeric (daily open) |
HighD | HighD(PeriodsAgo) | numeric (daily high) |
LowD | LowD(PeriodsAgo) | numeric (daily low) |
CloseD | CloseD(PeriodsAgo) | numeric (daily close) |
OpenW | OpenW(PeriodsAgo) | numeric (weekly open) |
HighW | HighW(PeriodsAgo) | numeric (weekly high) |
LowW | LowW(PeriodsAgo) | numeric (weekly low) |
CloseW | CloseW(PeriodsAgo) | numeric (weekly close) |
OpenM | OpenM(PeriodsAgo) | numeric (monthly open) |
HighM | HighM(PeriodsAgo) | numeric (monthly high) |
LowM | LowM(PeriodsAgo) | numeric (monthly low) |
CloseM | CloseM(PeriodsAgo) | numeric (monthly close) |
OpenY | OpenY(PeriodsAgo) | numeric (yearly open) |
HighY | HighY(PeriodsAgo) | numeric (yearly high) |
LowY | LowY(PeriodsAgo) | numeric (yearly low) |
CloseY | CloseY(PeriodsAgo) | numeric (yearly close) |
Price calculation shortcuts
These take no arguments — they use the current bar's OHLC automatically.
| Function | Signature | Returns |
|---|
AvgPrice | AvgPrice | numeric |
MedianPrice | MedianPrice | numeric |
TypicalPrice | TypicalPrice | numeric |
WeightedClose | WeightedClose | numeric |
Counting and occurrence
| Function | Signature | Returns |
|---|
CountIF | CountIF(Condition, Length) | numeric |
MRO | MRO(Condition, Length, Occurrence) | numeric (bars ago of Nth occurrence) |
LRO | LRO(Condition, Length, Occurrence) | numeric (bars ago of Nth-oldest occurrence) |
SummationIf | SummationIf(Condition, Price, Length) | numeric (conditional sum; only adds Price when Condition is true) |
IFFString | IFFString(Condition, TrueVal, FalseVal) | string (inline ternary returning a string) |
Volume-based
| Function | Signature | Returns |
|---|
AccumDist | AccumDist(Length) | numeric |
OBV | OBV | numeric (no args; On Balance Volume) |
VolumeROC | VolumeROC(Length) | numeric (volume rate of change) |
VolumeOsc | VolumeOsc(ShortLen, LongLen) | numeric (volume oscillator; short MA − long MA of volume) |
PriceVolTrend | PriceVolTrend | numeric (no args; cumulative price-volume trend) |
LWAccDis | LWAccDis | numeric (no args; Larry Williams Accumulation/Distribution) |
Statistical
| Function | Signature | Returns |
|---|
IFF | IFF(Condition, TrueVal, FalseVal) | numeric (inline ternary) |
Fisher | Fisher(Price) | numeric (Fisher transformation; input should be normalized −1 to +1) |
FisherINV | FisherINV(Price) | numeric (inverse Fisher transformation) |
AvgDeviation | AvgDeviation(Price, Length) | numeric (mean absolute deviation) |
Variance | Variance(Price, Length) | numeric (population variance) |
Kurtosis | Kurtosis(Price, Length) | numeric (excess kurtosis) |
Skew | Skew(Price, Length) | numeric (skewness) |
PercentRank | PercentRank(PriceValueToRank, PriceValue, Length) | numeric (percent rank of value within lookback) |
Covariance | Covariance(Price1, Price2, Length) | numeric |
Quartile | Quartile(Price, Length, Q) | numeric (Q: 1=25th, 2=50th, 3=75th) |
TrimMean | TrimMean(Price, Length, TrimPct) | numeric (trimmed mean) |
Mode | Mode(PriceValue, Length, Type) | numeric (modal value) |
HarmonicMean | HarmonicMean(Price, Length) | numeric |
Moving averages extended
| Function | Signature | Returns |
|---|
SmoothedAverage | SmoothedAverage(Price, Length) | numeric (Wilder smoothing) |
Miscellaneous
| Function | Signature | Returns |
|---|
BarAnnualization | BarAnnualization | numeric (no args; bars-per-year factor) |
LastBarOnChart | LastBarOnChart | truefalse (no args; true on last bar) |
Custom functions (commonly available)
These ship as f_* function files with many MultiCharts installations. They are not built-in keywords — you must have the corresponding function study (e.g. f_StochRSI) in your PowerLanguage Editor for the call to compile. If missing, create a new function study and paste the implementation from the source below.
| Function | Signature | Returns |
|---|
StochRSI | StochRSI(Price, RSILen, Length) | numeric (0–1; Stochastic of RSI) |
supertrend | supertrend(ATRLen, Mult) | numeric (trend line value; positive = uptrend support, negative = downtrend resistance) |
NVI | NVI(StartValue) | numeric (Negative Volume Index; updates only when volume decreases) |
PVI | PVI(StartValue) | numeric (Positive Volume Index; updates only when volume increases) |
Coppo | Coppo(N1, N2, N3) | numeric (Coppock Curve; WMA of two ROC periods — uses Close of Data2) |
LWTI | LWTI(Price, Period, Length) | numeric (Larry Williams Trading Index; 0–100 oscillator) |
TVI | TVI(Price, Vol, MinTickValue) | numeric (Trade Volume Index; cumulative directional volume) |
SharpeRatio | SharpeRatio(Period, IntRate, CalculateRatio, InitCapital) | numeric (portfolio-level; Period: 0=monthly, 1=daily; requires position history) |
WRSI | WRSI(Length, Price) | numeric (0–100; Wilder RSI with session reset — original Wilder smoothing) |
NewMA | NewMA(Price, Length) | numeric (Heikin-Ashi TEMA hybrid moving average) |
Candlestick patterns
These return 1 if the pattern is detected, 0 otherwise. Multi-output variants populate ref variables.
| Function | Signature | Returns |
|---|
C_Doji | C_Doji(Percent) | numeric (1 if doji; body within Percent of range) |
C_Hammer_HangingMan | C_Hammer_HangingMan(Length, Factor, oHammer, oHangingMan) | numeric; populates 2 ref vars |
C_BullEng_BearEng | C_BullEng_BearEng(Length, oBullEng, oBearEng) | numeric; populates 2 ref vars |
C_BullHar_BearHar | C_BullHar_BearHar(Length, oBullHar, oBearHar) | numeric; populates 2 ref vars |
C_MornDoji_EveDoji | C_MornDoji_EveDoji(Length, Percent, oMornDoji, oEveDoji) | numeric; populates 2 ref vars |
C_MornStar_EveStar | C_MornStar_EveStar(Length, oMornStar, oEveStar) | numeric; populates 2 ref vars |
C_PierceLine_DkCloud | C_PierceLine_DkCloud(Length, oPierce, oDkCloud) | numeric; populates 2 ref vars |
C_ShootingStar | C_ShootingStar(Length, Factor) | numeric (1 if shooting star) |
C_3WhSolds_3BlkCrows | C_3WhSolds_3BlkCrows(Length, Factor, o3WhSolds, o3BlkCrows) | numeric; populates 2 ref vars |
Gotchas
MarketPosition(N), EntryPrice(N), BarsSinceEntry(N) are position history, NOT bar offset
A natural-looking expression like MarketPosition(1) reads as "the market position one bar ago" — but it actually returns the position one trade ago. So MarketPosition(1) on bar 50, when the strategy has been flat for the last 30 bars, returns whatever the previous closed position was (long or short), not 0.
The same trap applies to EntryPrice(N) and BarsSinceEntry(N). EntryPrice(1) returns the entry price of the previous closed position, not the entry price one bar ago. BarsSinceEntry(1) returns the bars-since-entry of the previous position, not the current position minus one.
To detect a position transition between bars (e.g. "did we just enter long?"), store the previous bar's position at the END of each bar:
Variables:
_prevMP(0);
If MarketPosition <> _prevMP Then Begin
// transition just happened this bar
...
End;
_prevMP = MarketPosition; // end of bar
This is the canonical pattern. Don't rely on MarketPosition(1) for transition detection.
Bars are labeled by their CLOSE time, not open time
A 60-minute bar covering 15:00–16:00 has Time = 1600, not Time = 1500. A filter like If Time = 1500 Then … will never match that bar.
To check whether the current bar is the first bar of the night session at 15:00, write:
If Time = 1600 Then ... // for 60-min bars
If Time = 1505 Then ... // for 5-min bars (first close after 15:00)
If Time = 1501 Then ... // for 1-min bars
Add one bar's worth of minutes to the session-start clock time.
Variable names must not match built-in function names or reserved letters
PowerLanguage is case-insensitive. If you declare Variables: dmiPlus(0); and then call dmiPlus = DMIPlus(14);, the compiler sees the variable and function as the same identifier — the variable shadows the function and the call fails. This applies to every built-in function: Average, RSI, CCI, ADX, MACD, Stochastic, BollingerBand, Highest, Lowest, etc. Especially dangerous are function names that look like natural variable names: Range, Momentum, Median, Correlation, Sign, Last, Slippage, Margin.
The single-letter data-series aliases are also reserved and cannot be used as variable or loop-counter names: C(Close), D(Date), H(High), I(OpenInterest), L(Low), O(Open), T(Time), V(Volume). Because PL is case-insensitive, i, c, l, v, etc. are all off-limits. This is especially easy to hit with i in For loops.
Use a different name — abbreviate, add a suffix, or prefix:
// WRONG — i is reserved (alias for OpenInterest)
For i = 1 To 10 Begin ... End;
// RIGHT — use ii, idx, cnt, n, etc.
For ii = 1 To 10 Begin ... End;
// WRONG — shadows the built-in DMIPlus function
Variables: dmiPlus(0);
dmiPlus = DMIPlus(14); // compile error
// RIGHT
Variables: dpVal(0);
dpVal = DMIPlus(14); // works
Inputs are read-only
You cannot assign to an Input inside a script. If you need a mutable copy, declare a Variable and copy from the Input once.
Variable types are fixed at first assignment
Variables: x(0); makes x numeric for the life of the script. You can't later assign a string to it. Same for True/False initial values (bool) and "" (string).
Many keywords can't appear as values on the right-hand side of =
A common new-user mistake is to write Value1 = SomeKeyword; for a keyword that looks identifier-like in the documentation but is actually a syntactic construct. PowerLanguage will throw "syntax error, unexpected '…'" or "Wrong syntax of '…'" when you do this. Empirically, the following classes never work as RHS values:
Whole keyword classes:
| Class | Example keywords | Why |
|---|
| Type / declaration words | Numeric, String, TrueFalse, Variable, Var, NumericSeries, IntraBarPersist | Used inside Inputs: / Variables: / Arrays: blocks |
| Control flow / operators | If, Then, Else, For, While, Begin, End, To, DownTo, Switch, Case, and, or, not | Reserved syntax |
| Script-level attributes | IntraBarOrderGeneration, LegacyColorValue, RecoverDrawings, AllowSendOrdersOn…, PortfolioEntriesPriority | Used in [Attr = value]; form at script start |
| Output statements | Print, FileAppend, FileClose, FileDelete, ClearDebug, ClearPrintLog, File, MessageLog, PlaySound | Statement-shaped, no return value |
| DLL-calling directives | DefineDllFunc, external, method, OnCreate, OnDestroy, ThreadSafe, plus C type names (int, lpstr, bool, …) | Statement / declaration syntax |
| Expert Commentary | #BeginCmtry, #EndCmtry, CheckCommentary, AtCommentaryBar | Paired-block directives |
Preprocessor (#-prefixed) | #BeginCmtry, #EndCmtry, #Return, #Events | Reserved positions; #BeginCmtry in particular opens a commentary block that runs to #EndCmtry |
| Connector words | Bar, Bars, Day, Days, Point, Points, Tick, Ticks, Ago, Next, This, Today, Yesterday, Market, Contract, Contracts | Used in compound phrases ("5 bars ago", "next bar at market") |
Other rules of thumb:
- A keyword name that contains a space in the official docs (e.g.
DateTime bar update, Cancel Alert) cannot be used as a single identifier — PowerLanguage parses only the first word and chokes on the rest.
- Single-letter data-series aliases (
C=Close, D=Date, H=High, I=OpenInt, L=Low, O=Open, T=Time, V=Volume) are reserved — using them with parentheses like C(Close) causes "A keyword/variable is used as a function". Use square brackets for barsback: C[1].
- A handful of names in otherwise-value-rich categories are reserved syntactic tokens:
Data (used as Close of Data2), Call / Put / Strike (option-context syntax), OptionType, DeltaType, RevSize, BoxSize.
- Procedure keywords like
ScrollToBar, PlaceMarketOrder, ChangeMarketPosition, and all PMM action keywords (pmms_strategy_resume, pmms_strategy_pause, pmms_strategy_close_position, pmms_strategy_deny_*, pmms_strategy_allow_*, pmms_strategies_*_all) perform an action and do NOT return a value — assigning them to Value1 causes "Function must have a return value". Call them as standalone statements: ScrollToBar(1, 0);.
- Signal/portfolio-only keywords like
Portfolio_CurrencyCode, StrategyCurrencyCode, InitialCapital cause "X is not applicable to this type of study" when used in an Indicator. They only work in Signal studies.
- Drawing-object accessors (any
Rectangle*, TL_*, Arw_*, Text_*, or MC_TL_*/MC_Arw_*/etc. function ending in Get/Set/Delete/New/…) take at least one drawing-object ID argument — never use them as bare values.
- Setter keywords (
Set*, Portfolio_Set*, pmm_set_*, or any name containing _set_) are statement-shaped — they always require at least one value argument and don't return a value.
- Lowercase-prefix functions (e.g.
getTPOinfo, getplotstyle) usually take parameters; the unusual lowercase naming is the signal.
- String-returning keywords like
Description, Symbol, GetCurrency, BarType_uid, anything ending in Name / Description / Listed / ToStr — can be assigned only to a string variable, not the numeric Value1.
- Boolean-returning keywords like
Is64BitProcess, MouseClickShiftPressed, AlertEnabled, PosTradeIsOpen, PosTradeIsLong, pmms_strategy_is_paused — use them inside an If condition (If Is64BitProcess Then ...); direct assignment to Condition1 sometimes fails because PowerLanguage returns numeric 0/1 instead of TrueFalse for some "logical" functions. Exception: MarketPosition_at_Broker_for_The_Strategy looks boolean but returns numeric 1/0/-1 (market position) — use Value1 = X;, not If X Then.
Quick error → fix lookup
If MultiCharts gives you one of these errors when using a keyword:
| Compile error | Likely cause | Fix |
|---|
syntax error, unexpected 'X' | X is a reserved syntactic token (declaration / control flow / connector) | Don't use it as a value; it belongs in a different syntactic position |
Wrong syntax of 'X' | X is a directive (e.g. DefineDllFunc) | Use the documented statement form, not as RHS |
Commentary end is expected before end of file | You used #BeginCmtry without #EndCmtry | Pair them, or skip the construct |
Invalid number of parameters. N parameter(s) expected | Function needs N args you didn't pass | Look up the signature in powerlanguage-keywords-reference and pass the right number |
Types are not compatible | RHS returns a type incompatible with the LHS variable | Assign string→string var, bool→bool var, numeric→Value1 |
A keyword/variable is used as a function | Using a data-series alias with parentheses, e.g. C(Close) | Use square brackets for barsback: C[1], or no brackets: Value1 = C; |
Function must have a return value | Assigning a procedure keyword (e.g. ScrollToBar) to a variable | Call as a standalone statement: ScrollToBar(1, 0); |
X is not applicable to this type of study | Using a signal-only keyword in an Indicator (e.g. InitialCapital) | Move to a Signal study, or remove the keyword |
When in doubt, look up the keyword in the powerlanguage-keywords-reference skill — the signature line shows whether it's used as KeywordName(args) (callable function) or in a larger construct (then it can't be the whole RHS).
Pre-generation checklist
Before writing any PowerLanguage code, verify every item below. Do not skip steps — each one maps to a real compile error encountered during testing.
- Script type matches intent. Indicator (plots, no orders), Signal (orders, no plots), or Function (returns a value)?
- Declarations exist and come first.
Inputs: → Variables: → Arrays: → code. Every variable used anywhere — including loop counters — must be declared.
- No variable-name collisions. Check every name in
Variables: against:
- Built-in functions:
Average, RSI, CCI, ADX, MACD, DMIPlus, DMIMinus, Stochastic, BollingerBand, Highest, Lowest, Range, Momentum, Median, Correlation, Volatility, MoneyFlow, Summation, Cum, Sign, Last, Total, etc.
- Single-letter aliases:
C, D, H, I, L, O, T, V (and their lowercase forms — i as a loop counter is the #1 trap).
- Use suffixed names:
rsiVal, atrVal, dpVal, avgVal, runTotal, idx, nn, cnt.
- Function signatures are correct. Check every function call:
- Length-only functions (
CCI, ADX, DMIPlus, DMIMinus, AvgTrueRange, PercentR, MoneyFlow, Volatility, RSquared, AccumDist) take no Price parameter.
Stochastic takes 11 params (4 are output ref vars that must be declared).DirMovement takes 10 params (6 are output ref vars).AdaptiveMovAvg takes 4 params (Price, EffRatioLen, FastAvgLen, SlowAvgLen).Parabolic takes 1 param (AfStep only).- If unsure, look it up in the "Common built-in functions" tables above.
- Order syntax is complete. Every order has: a unique name string, quantity + unit, and the
at keyword — Next Bar at Market, Next Bar at <price> Stop, Next Bar at <price> Limit, or This Bar on Close.
- Order names are unique. No two orders in the same Signal share a name string.
- Semicolon rule.
End before Else → no semicolon. End at statement boundary → semicolon.
- Study-type restrictions. No
Plot in Signals. No Buy/Sell in Indicators. No MarketPosition/EntryPrice in Indicators.
Post-generation self-review
After writing PowerLanguage code, re-read it against this list before presenting it. Fix any issues silently — do not present code that fails these checks.
- Walk the
Variables: block. Read each name aloud — does it match any built-in function or single-letter alias? If yes, rename it.
- Walk every function call. Count the arguments. Compare to the signature table. Pay special attention to Length-only functions (no Price) and multi-output functions (ref vars declared?).
- Walk every order line. Is the
at keyword present? Is the name string unique within this Signal?
- Walk every
End. Is the next token Else? If yes → no semicolon. Otherwise → semicolon.
- Walk every
For/While. Is the loop counter declared in Variables:?
- Check type consistency. Numeric functions →
Value1 or numeric variable. String functions (anything ending in ToStr, Name, Description) → string variable. Don't assign strings to Value1.
