memberinfo template - what variable do I 'pass' to a PHP script for a member's userID

[criscokid]

I've creating small PHP script that I'll be using to output info on the Memberinfo template by way of a pluugin.

What variable do I use in the PHP script for the userID of the profile I'm looking at at the time?

Assuming my userID is 1 and I'm looking at the profile of the person whose userID is 5 - I want userID=5 to be passed through to the PHPscript or 10 if their userID happens to be 10.