reading specials from a file

 tpic specials or any number of consecutive \special can be written to a file and read. The TeX format is

\special{file=file_name}

\special is written in file_name.

The search path for the file is identical to the one for a BMP file so the Current Directory and the directory indicated by -gdat: are searched.

If  % appears in the file, everything until the 0x0a newline code is ignored.

Only the parts enclosed by {...} in \special{...} in the file are interpreted.  Other parts are ignored.

Even if there is { } nesting in this {...}, the processing is correct.  In addition, all of the character codes below 0x20 in {...} are replaced by spaces.

One {...} is allowed to contain a maximum of 4000 bytes.