My printer

• Labelary – Online ZPL preview tool, also has good documentation and information regarding the ZPL
• Zebra Programming Guide – Official guide

It is possible to make newlines for every new command. Some tutorials tend to stack several related, but different, commands on the same line.

^XA
 
^FX The FX command starts a comment that ends at the next tilde 
or caret, but should be correctly terminated with a field separator command/symbol ^FS
 
^FX Print a box, 80 by 80 points (1cm) ^FS
^FO16,8^GB80,80,5^FS
 
^XZ