VDM-10 Language Manual

Appendix A. The Syntax of the VDM Languages
externals = ‘ext’, var information, { var information } ;
var information = mode, name list, [ ‘:’, type ] ;
mode = ‘rd’ | ‘wr’ ;
exceptions = ‘errs’, error list ;
error list = error, { error } ;
error = identifier, ‘:’, expression, ‘->’, expression ;
A.6.6
Instance Variable Definitions (VDM++ and VDM-RT)
instance variable definitions = ‘instance’, ‘variables’,
[ instance variable definition,
{ ‘;’, instance variable definition } ] ;
instance variable definition = access assignment definition
| invariant definition ;
access assignment definition = ([ access ], [ ‘static’ ]) | ([ ‘static’ ], [ access ]),
assignment definition ;
invariant definition = ‘inv’, expression ;
A.6.7
Synchronization Definitions (VDM++ and VDM-RT)
synchronization definitions = ‘sync’, [ synchronization ] ;
synchronization = permission predicates ;
permission predicates = permission predicate,
{ ‘;’, permission predicate } ;
permission predicate = ‘per’, name, ‘=>’, expression
| mutex predicate ;
mutex predicate = ‘mutex’, ‘(’, ‘all’, ‘)’
| ‘mutex’, ‘(’, name list ‘)’ ;
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