Fixed member links are a form of updating the placement of CATIA V5 parts in an assembly. Specifically, it involves setting the transformation matrix in Windchill and determining if the parts are eligible in CATIA.

A fixed member link does not have a constraint in CATIA V5. A part in CATIA V5 is constrained if it cannot move.

If the member link is fixed and has no constraints, then it can be used to build and iterate assemblies.