This MOF Format Specification is riddled with C-style ("//") comments but the the allowed structure of actual MOF file comments are not shown in the BNF (which uses BNF improperly, IMO: "aliasIdentifer = "$" IDENTIFIER // NO whitespace !").
I have found many examples of MOF files that use:
/* comments */
// comment
But these were not in the context of defining the MOF format itself.
According to the DMTF specification, MOF files support "// ..." and "/* ... */" for comments.
See section "5.4 Comments" of http://www.dmtf.org/sites/default/files/standards/documents/DSP0221_3.0.0a.pdf for details.
(Link found at http://www.dmtf.org/standards/cim - first document in the the "DMTF Specifications" section, titled "DSP0221").