Here is a list of all namespace variables with links to the namespace documentation for each variable:

BOM : fe::utf8
Bom : fe::utf8
Default_Inlined_Size : fe
EoF : fe::utf8
Ext : fe::dl
Invalid : fe::utf8
Max : fe::utf8
Null : fe::utf8
Path_Sep : fe::sys
Path_Sep_Word : fe::sys
Path_Sep_word : fe::sys
Which : fe::sys