Hello,

Please, read any tutorial to regular expressions - you can use the | symbol in regular expressions with the meaning of OR, like this:

1. expression: format=pdf
2. expression: print=1
Combined expression: (format=pdf)|(print=1)

But be careful, because of the way Joomla stores parameters in the database, you need to escape the | symbol, so you need to type the expression like this:

(format=pdf)\|(print=1)

If the expressions are more complicated, the Variables filtering may be a better choice.

Best regards,
ARTIO Support Team