5.1.7.1 IfcSingleProjectInstance
5.1.7.1.1 Semantic definition
The global rule verifies that only a single (as maximum) instance of IfcProject exists.
5.1.7.1.2 Formal representation
RULE IfcSingleProjectInstance FOR
(IfcProject);
WHERE
WR1 : SIZEOF(IfcProject) <= 1;
END_RULE;