Every message the tools can produce has a number. 41 of them so far.
The numbering is there so you can search for IG211 and land on
this page rather than on a forum thread, and so the same problem has the same
name in every program that handles IGL.
Typing igl explain IG211 gives you the same text in a terminal,
and the editor shows it beside the line that caused it.
| Code | Severity | When | Summary |
|---|---|---|---|
| IG001 | error | syntax | unexpected token |
| IG002 | error | syntax | unterminated string |
| IG003 | error | syntax | unknown block header |
| IG004 | error | syntax | statement is not indented |
| IG005 | error | syntax | block belongs to an unsupported profile |
| IG006 | error | syntax | non-ascii character outside an accepted position |
| IG007 | error | syntax | malformed expression |
| IG008 | error | syntax | unknown or malformed unit |
| IG009 | error | syntax | named block is missing its identifier |
| IG010 | warning | syntax | block identifier does not begin with an uppercase letter |
| IG011 | warning | syntax | a block this implementation does not honour |
| IG101 | error | semantic | reference to an undeclared entity |
| IG102 | error | semantic | duplicate name in the global namespace |
| IG103 | error | semantic | malformed or unknown isotope ratio |
| IG104 | error | semantic | mismatched element symbols across a ratio |
| IG105 | error | semantic | duplicate of a block that must be unique |
| IG106 | error | semantic | no reference standard resolvable for a ratio |
| IG107 | error | semantic | unresolved symbol in an expression |
| IG108 | warning | semantic | local symbol shadows a global one |
| IG109 | error | semantic | ill-formed qualified name |
| IG110 | error | semantic | assignment to a read-only symbol |
| IG201 | error | validation | value outside the admissible range |
| IG202 | error | validation | value does not match the expected type |
| IG204 | error | validation | unit incompatible with the expected dimension |
| IG205 | error | validation | unit omitted where several are admissible |
| IG210 | error | validation | unknown property for this block type |
| IG211 | error | validation | required property missing |
| IG212 | warning | validation | recommended property absent |
| IG213 | error | validation | mutually exclusive properties both present |
| IG214 | error | validation | physically inadmissible configuration |
| IG215 | error | validation | mixing fractions do not sum to one |
| IG301 | error | execution | solver failed to converge |
| IG302 | error | execution | numerical instability |
| IG303 | error | execution | division by zero during evaluation |
| IG304 | error | execution | negative remaining fraction |
| IG305 | error | execution | reaction progress outside 0 to 1 |
| IG306 | warning | execution | a statement the chosen progress does not read |
| IG401 | error | backend | required backend unavailable |
| IG402 | error | backend | backend reported a failure |
| IG403 | error | backend | backend communication timeout |
| IG404 | error | backend | a backend series read outside what it recorded |
Raised while reading the file, before anything has been looked up.
The parser reached a token that cannot appear at this position.
This is the fallback syntax diagnostic. When a more specific code applies it is emitted instead, so IG001 usually means the line does not match any statement family: an assignation, a reference, an expression, a species declaration or a list.
A string literal was opened with a double quote and never closed before the end of the line. Strings do not span lines in IGL.
A non-empty line starts at column 0 but does not name a known block.
Block headers are recognised only at column 0, and statements must be indented. A statement written flush left is therefore read as a block header, which is the most common cause of this diagnostic.
A line inside a block begins at column 0 but is not a block header.
See IG003: the two diagnostics describe the same mistake from opposite sides. IG004 is emitted when the token is a known statement key, IG003 when it is not.
The model uses a block from the Extended profile and this implementation declares Core conformance only.
Implementations must report the block rather than skip it. Silently ignoring an Extended block would produce a numerically plausible result from an incomplete model, which is worse than a refusal.
Non-ASCII characters are accepted only inside string literals, and as the unit aliases 'micro sign' and 'per mille sign', which the lexer normalises to their ASCII forms.
Isotope notation is ASCII only. Typographic rendering such as a lowercase delta followed by a superscript mass belongs to report and plot backends, never to source files, structured data files or the intermediate representation.
The right-hand side of an expression statement is not a valid expression.
Operators are + - * / and ^. Exponentiation is right associative and binds tighter than multiplication. A species token is not a valid operand; reach a species-valued quantity through a qualified name such as Groundwater.Cr(VI).
The trailing run of a statement is not a unit the registry knows.
A unit is a product or quotient of unit factors, each optionally raised to an integer power: 1/d, mol/kgw, mg/L, m^3, J/mol/K. Composite units are registered whole rather than composed, so `mol/kgw` is one entry and `mol/kgww` is not an entry at all.
The diagnostic lists the units the property's dimension admits.
A block that registers an entity carries its name on the header line.
v0.3 wrote the name on an indented line below the header. v0.4 puts it on the header, which is what makes implicit block termination unambiguous.
The identifier on a block header line begins with a lowercase letter.
Entity names and chemical species are capitalised, keywords and enumerated values are not, which is what lets a reader tell them apart by shape. The rule covers block identifiers only: parameter names such as `alpha_red` are conventionally lowercase and never warn.
A lowercase entity name still parses. The warning exists because it is almost always a slip rather than a choice.
The model uses a block the language defines and this implementation does not read. It is not refused, and the run produces everything else the model asks for; the block simply had no effect.
Reported rather than passed over, because a block that vanishes leaves a model looking as though it says something no run reads. The results are then correct for a model nobody wrote.
Distinct from IG005, which refuses a block belonging to a profile the implementation does not claim at all. Here the profile is claimed and this one construct within it is not implemented, which a conformance report should be able to say without the two being confused.
Raised when something a model refers to cannot be found, or is found twice.
An identifier is used as a reference but no entity of the expected type carries that name.
Symbol resolution is a whole-file pass, so declaration order does not matter and a forward reference is legal. This diagnostic therefore means the name is absent from the model entirely, not that it appears too late.
Two entities are declared under the same name.
IGL uses one global namespace for every named entity, whatever its type. A reservoir and a process cannot share a name. This is the condition for the extension pattern to work: FRACTIONATION Reduction has to designate exactly one object.
An isotope ratio does not match the normative form, which is mass number followed by element symbol on both sides of a slash.
Forms accepted by earlier drafts, such as an element followed by two mass numbers, or a bare single isotope, are not valid. A fractionation is always relative, so there is no single-isotope form.
The two element symbols of a ratio differ.
An inter-element ratio has no meaning in this position. The check costs nothing and catches the most frequent transcription error.
A block appears more than once although the registry declares it unique.
EXPORT and PLOT may repeat. Every other unnamed block occurs at most once per file.
A delta value was given for a ratio whose reference standard cannot be resolved, either from the loaded IGDB databases or from a STANDARD block.
A delta is meaningless without the standard it is measured against, and the engine needs the certified ratio to convert the delta into the internal representation.
An identifier inside an expression matches nothing in the local scope of the enclosing block, nor in the global symbol table.
A cycle among parameter definitions reports the same code, with the full chain listed in the diagnostic.
A block-local parameter carries the name of a global parameter.
Shadowing is legal, because forbidding it would make library-style PARAMETERS blocks fragile. It is worth a warning because it is rarely intentional.
A qualified name has other than two components, or its head resolves to a scalar rather than to an entity with a local scope.
Property access does not nest: A.B is valid, A.B.C is not.
A parameter bound from a backend export is read only.
Names introduced by an `export ... to ...` statement in a PHREEQC block are produced by the chemistry backend. Rebinding one would silently discard the computed value.
Raised when a block has a statement it should not, or is missing one it needs.
A property carries a value the domain does not admit: a negative concentration, a negative volume, a mixing fraction outside zero to one, a fractionation factor that is zero or negative.
The value given for a property is not of the type the schema declares, or is outside the set of values an enumerated property admits.
Covers a quoted number where a number is expected, a malformed date or version literal, a species token where a string is expected, and an enumerated value the property does not list. The diagnostic prints the admissible values when the property is enumerated.
The unit given for a property belongs to a different dimension than the one the property expects.
A unit may be omitted only where the property admits exactly one, or where a default is declared in the UNITS block. Otherwise the value is ambiguous.
The statement key is not part of the schema of the enclosing block.
The diagnostic lists the admissible keys, and suggests the closest one when the edit distance is small enough.
The block schema declares a property as required and it is absent.
For PROCESS, the required set depends on the value of `type`. A mixing process requires two or more sources and a product, and requires neither reactant nor mechanism.
A property marked as recommended is absent. Execution proceeds.
The recommended keys of META exist for reproducibility, not for computation. A published model without a language version or a description is harder to reuse than one that carries them.
A block declares more than one member of an exclusive group.
A FRACTIONATION block carries exactly one of alpha, epsilon, an inline law, a law reference or a law file. Two of them would leave the fractionation factor undetermined.
The model is internally consistent but describes a system that cannot exist: a process whose reactant and product are the same species, a reservoir with no tracked isotope taking part in a fractionating process, a stopping condition that is already satisfied at the initial state.
The source fractions of a mixing process must sum to one within 1e-6.
When a fraction is a parameter, the check runs after parameter evaluation. It is deferred entirely when the parameter is a FIT target, since its value is not known before calibration.
Raised by the calculation engine. You will never see these from checking alone.
The numerical solver did not reach its tolerance within the allowed iterations.
The diagnostic reports the simulation time at which convergence failed, which is usually enough to locate the stiff process.
A state variable became non-finite during integration.
The usual cause is a rate constant far larger than the inverse of the timestep. Reducing `step` in the MODEL block, or letting the engine choose an adaptive step, resolves most occurrences.
An expression divided by a quantity that evaluated to zero at run time.
Temperature-dependent fractionation laws written against T are the common case, when the enclosing scope declares no temperature and the default resolves to zero rather than to a physical value.
A reactant pool went below zero.
This is a mass balance failure rather than a modelling choice, and the engine stops instead of clamping, because a clamped pool silently breaks the isotopic balance downstream.
An `extent` evaluated to a value that is not a fraction of a reactant.
A literal is bounded by the validator, which can read it. An expression cannot be judged before it is evaluated, so the check happens while the model runs, and it happens rather than being skipped: a fraction above one leaves a negative amount behind, and the closed form of a distillation then takes the logarithm of a negative number. A composition arrives, it is not a number, and nothing says which of the two was at fault.
The common source is a progress computed from a backend, where the denominator was not the total the numerator was measured against.
A process states an `extent` and the model advances by time, or the reverse.
The two are alternative ways of driving a model, not layers of one. Under `progress time` an engine integrates a rate law and never consults an extent; under `progress extent` it never advances a clock. The statement is therefore not wrong, it is unread, which is worse than wrong because the model looks as though it says something it does not.
It is a warning rather than an error because the model still has a defined meaning: the unread statement changes nothing.
Raised when an outside program such as PHREEQC is needed, missing, or unhappy.
The model requires a backend this installation does not provide.
An implementation must not substitute an approximation of its own for a missing backend. A PHREEQC block without PHREEQC is an error, not an invitation to guess the speciation.
The backend ran and returned an error. Its own message is included verbatim in the diagnostic, since it is generally more precise than anything IGL could infer from the failure.
The backend did not answer within the configured timeout.
A parameter exported under `mode series` was read at an instant the backend never reported.
The engine holds the last recorded state until the next one, which is true: it is the last thing the chemistry said. It does not hold the first state backwards in time, because the backend said nothing about that instant and a value invented there would be indistinguishable from one it computed.
The usual cause is a model whose clock starts before the backend's, or a SELECTED_OUTPUT that does not record the initial solution.