Make arrays out of them...easier, cleaner and more fun!!!!!!
<FORM ACTION="<?=$PHP_SELF;_?>" METHOD="post">
<INPUT TYPE=hidden NAME="write_file" VALUE="yes">
<INPUT TYPE=checkbox NAME="ckbox1[]" VALUE="1"> Box 1<BR>
<INPUT TYPE=checkbox NAME="ckbox1[]" VALUE="2"> Box 2<BR>
<INPUT TYPE=checkbox NAME="ckbox1[]" VALUE="3"> Box 3<BR>
<INPUT TYPE=checkbox NAME="ckbox2[]" VALUE="1"> Box 1<BR>
<INPUT TYPE=checkbox NAME="ckbox2[]" VALUE="2"> Box 2<BR>
<INPUT TYPE=checkbox NAME="ckbox2[]" VALUE="3"> Box 3<BR>
<INPUT TYPE=submit>
</FORM>
Then all your stuff fits into a nice package as 'chbox1[]' and you can grab it and make use of some simple array tools...explode, implode, whatever you need...
Or, something like that... 😉