All new official meta-commands are required to have a ! prefix, and have the command name be in all caps. (It is strongly recommended that unofficial ones have the same format.) BFC (0 BFC ...) is too old to have that. Same with MPD (0 FILE ...). Comments are recommended to have a // prefix (0 // Some comment...).
See the Line Type 0 section of the LDraw 1.0.2 spec.
See the Line Type 0 section of the LDraw 1.0.2 spec.