Modeling Syntax

General syntax conventions

Variable names are case sensitive and cannot contain special characters such as a period “.”. They can contain an underscore “_”, but if they do they are not compatible with S-PLUS syntax. The first character of a variable name cannot be an underscore “_”.
Column names are case sensitive and can contain special characters. However, if a column name contains a blank space, the data must be given in CSV format, and a special argument, /csv, must be given to the engine.
Line boundaries are not significant. Statements can span multiple lines, except for comments. Characters that denote comments include.
# comment... end-of-line (S-PLUS convention)
/* comment... */ (multi-line, non-nesting, C convention)
// comment... end-of-line (C++ convention)
Block delimiters: { …} (curly brackets, S-PLUS convention)
Statement delimiter: An optional semicolon (S-PLUS convention)
Sub-statement delimiter: An optional comma
Assignment operators:
“=” sign (S-PLUS convention)
“<-” (S-PLUS convention)
Declaration of variables: Variable types are double precision so scoping is not needed (S-PLUS convention). Variables are of two types:

•Declared variables are introduced by a declaration, such as deriv or real. These can be changed at points in time, such as in sequence statements.

•Functional variables are introduced by being assigned at the top level of a model, such as C=A1/V1. They are regarded as being computed “all of the time.”

Model member reference: Models inherently act as structure. “$” is the model component reference operator (S-PLUS convention)
Although the Phoenix Modeling Language uses the real variable for designating real numbers, double is also acceptable.