Appendix C: Changes

Main changes from the previous public proposal (23 January 1998):

• A basic specification may now be empty.
• A unit attribute has been generalized to a term.
• The grammar concerning ordinary and mixfix predicate and operation applications has been tightened up.
• The syntax of qualified predicate and operation symbols has been changed.
• A construct to qualify a variable identifier has been added.
• A free specification may now only be applied to a grouped specification.
• Lists of symbols and symbol maps now allow distinction to be made between sorts, operations, and predicates.
• The optional overall symbol map in an instantiation of a generic specification has been removed.
• Some minor bugs in the grammar have been eliminated.
• Concrete syntax for libraries has been added.