resources/metadata/84/altformats.csv - external/libphonenumber - Git at Google

 Format        ; Parent Format  ; Comment
 XXX XXX XXX   ; mobile_2/3/2/2 ; "Alternate mobile format"
 XX XX XXX XXX ; fixed_2/4/4    ; "Alternate format for big cities."
 XXXX XXX XXX  ; fixed_4/4-6    ; "Non-geographic numbers follow less rigid formatting patterns."
	Format ; Parent Format ; Comment
	XXX XXX XXX ; mobile_2/3/2/2 ; "Alternate mobile format"
	XX XX XXX XXX ; fixed_2/4/4 ; "Alternate format for big cities."
	XXXX XXX XXX ; fixed_4/4-6 ; "Non-geographic numbers follow less rigid formatting patterns."