Why is "Reserved" our Spc-4 name for mask x7F of byte 1 of Inquiry, rather than "Obsolete"?

Over time, the names I see we gave this field include:

"Device-Type Qualifier" in T10 S1-r17b.txt
"Device-type modifier" in T10 S2-r10l.pdf and http://en.wikipedia.org/wiki/SCSI_Inquiry_Command
"Reserved" in Spc-r11a.pdf and other T10 Spc since then

Anybody know why?

Curiously yours, thanks in advance,

P.S. I haven't yet checked the other prominent redefinitions of Inquiry (T10 Mmc Scsi, Sff Scsi, Ufi Scsi, etc).