Reorganized code to use a common symbol name validation routine. ...

Wrote logic to explicitly check for illegal first character in symbol names.
Wrote logic to check symbol names for illegal characters throughout.

Combined reserved and predfined symbols into a single data dictionary.

Implemented check to prevent namespaces with leading ENVIRO character.

Fixed a number of subtle bugs involving namespace handling for ...

variable names and references.

Added check to make sure a variable name does not contain DELIML or ...

DELIMR.

Cleaned up all manner of bugs having to do with variable names ...

containing whitespace and references involving them.

Added explicit check for nested variable references.

Changed API argument from InitialSymTbl to InitialSymTable.

Added code to verify that LegalVals is a list for each variable passed ...

in the initial symbol table.

Added to to insure that the initial namespace passed by the calling
program is also present in the NAMESPACE LegalVals list.

Added support for AllowNewNamespaces option. ...

Added debug output whenever a namespace is changed.

Added support for AllowNewVars API option.

Suppress attempts to name variables with leading $ or #.

Added code to prevent variable names beginning with DOLLAR.

Sorted error and warning messages in the source code.

Restrucured predefined symbols for ease of maintenance and to make use ...

of the platform module.

Corrected return logic in the face of an API error to use the newer ...

style return object.

Added predefined variable dump on direct invocation.

Implemented several pre-defined variables to reflect running system.

Changed return mechanics to use an object instead of a tuple of lists. ...

Changed error message for errors found at EOF to reflect this
location.

Moved direct invocation logic to end of file. ...

Added a __all__ entry at the end of the file to explicitly name the
public symbols.

Cleaned up the string too short/too long error messages.

Changed VarDescriptor base class to inherent from 'object'. This ...

makes it possible to use the 'super' operation when subclassing from
this base.

Changed the file open logic to only trap on an IO Error. Other errors ...

fall through and cause a Python error exit.  Necessary so that program
errors are not caught and treated like a bad file open.

Implemented the ELSE directive.

Retructured CondStack to prepare the way for ELSE directives.

Inhibited declaration/reference of null-named variable. ...

Inhibited declaration/reference of variables with whitespace in their
name.

Major code reorganization to fix problem with nested conditionals and ...

prepare the way for the ELSE operator.
Many other incidental bugs found and fixed.

Added Legal Values checking for all relevant types.

Cleaned up bugs in the bounds checking logic.

Further cleanup of API validation logic.

Added more detail to errors encountered while validating symbol table ...

passed to API.

Added further sanity checking of any symbol table passed into the API.