Restrictions and Limits

We have removed or extended some of the restrictions and limitations which were part of the original sources but some remain:

• The number of procedures and local modules is limited to 512 in each global module.
• The first 24 characters of module identifiers are significant only.
• The return type of functions must not be structured (well, this is already stated in the report) and set types as return types are accepted only if the range of ordinal values falls into the interval of [0..31].
• There is an upper limit of the total amount of space used for identifiers (which includes those identifiers in the directly or indirectly imported definition modules).
• The scope nesting level is limited to 64.
• The base type of sets is limited to the ordinal range of [0..MAX(INTEGER)]. This is the only restriction, that means that SET OF CHAR and other (even much larger base types) are perfectly legal.
• There may exist some pathological cases which could use up all available registers during the code generator. But so far, we don't have found an example to provoke that problem.

Note that some common restrictions are not imposed by Ulm's Modula-2 compiler:

• The set of case labels may cover any range (as long as the case expression is compatible to each of the case labels).
• Absolutely everything may be passed to a formal type ARRAY OF BYTE, including arbitrary constants. ARRAY OF WORD works similar but requires the actual argument to have a size which is a multiple of 4 (the size of WORD).