"I already know that!" Sure you do. If you want to print "G" you simply write:
." G"
Don't you? But what if you want to use a TAB character (ASCII 9)? You can't type in that one so easily, huh? You may even find it doesn't work at all!
Don't ever use characters outside the ASCII range 32 to 127 decimal. It may or may not work, but it won't be portable anyway. the word 'EMIT' may be of some help. If you want to use the TAB-character simply write:
9 emit
That works!