Most OOGL object file formats are free-format ASCII — any amount of white space (blanks, tabs, newlines) may appear between tokens (numbers, key words, etc.). Line breaks are almost always insignificant, with a couple of exceptions as noted. Comments begin with # and continue to the end of the line; they're allowed anywhere a newline is.
Binary formats are also defined for several objects; See Binary format, and the individual object descriptions.
Typical OOGL objects begin with a key word designating object type, possibly with modifiers indicating presence of color information etc. In some formats the key word is optional, for compatibility with file formats defined elsewhere. Object type is then determined by guessing from the file suffix (if any) or from the data itself.
Key words are case sensitive. Some have optional prefix letters
indicating presence of color or other data; in this case the order of
prefixes is significant, e.g.
CNMESH is meaningful but
NCMESH is invalid.