Definition from buildingSMART: A defined type of simple data type Integer. (Required since a select type, i.e. IfcSimpleValue, cannot include directly simple types in its select list).
In principle, the domain of IfcInteger (being an Integer) is all integer numbers. Here the number of bits used for the IfcInteger representation is unconstrained, but in practise it is implementation specific.
HISTORY New type in IFC Release 1.5.1.