PHP $_REQUEST['do'] -

i'm php beginner. don't see answer question in php manual.

i know request superglobal does, 'do' built php? found code in tutorial...

if (isset($_request['do']) && ($_request['do'] == 'add') )  

does 'do' mean form has been submitted? in case of information coming link...?

any values set in $_cookie, $_get, , $_post show in $_request means form submits data page has input element key of 'do' in example:

<input type="hidden" name="do" value="add" /> 

of course any html form element name of do, or cookie name of do, or static query string name of do.