Original: It is sometimes abbreviated to cu m , m3 , m ^ 3 or m ** 3 when superscript characters or markup can not be used ( i.e. in some typewritten documents and postings in Usenet newsgroups ) .
Simplified: It is sometimes abbreviated cu m , m3 , m ^ 3 or m ** 3 when superscript characters or markup are not available/accessible ( i.e. in some typewritten documents and postings in Usenet newsgroups ) .