How do I learn and store the current forum id#

[bigrover]

I am trying to find where I can learn the current forum id# so I can use it to manage output from form mod. I have one form I would like to use in multiple forums. I can specify the target forumid for the form output. I now need to know what forum the user was in when they initiated the action to use the form. Any help would be appreciated.

[Jaxel]

This is what I did for this mod:
https://vborg.vbsupport.ru/showthread.php?t=240629


<plugin active="1" executionorder="5">
<title>header GLOBAL info</title>
<hookname>global_start</hookname>
<phpcode><![CDATA[$forum = array('forumid' => $vbulletin->GPC['forumid']);
vB_Template::preRegister('header',array('forum' => $forum));]]></phpcode>
</plugin>