184.108.40.206.1 Semantic definition
IfcReal is a defined type of simple data type REAL. It is required since a select type (IfcSimpleValue), cannot directly include simple types in its select list.
In principle, the domain of IfcReal (being a Real) is all rational, irrational and scientific real numbers. Here the precision is unconstrained, but in practice it is implementation specific.
220.127.116.11.2 Formal representation
TYPE IfcReal = REAL; END_TYPE;