[development] What is gid in node_access table when realm = 'term_access'?

[Earl Miles]

Ron Parker wrote:
> So, I began searching Drupal and the internet trying to find out the 
> answer to this question:
> 
> What is the "gid" value in the node_access table referring to when the 
> realm = 'term_access'?
> 
> Can anyone explain or point me to a resource that will explain it?
> Thanks!

The 'gid' is the 'Grant ID' which identifies the group this grant belongs to. 
What this means is that every record in the node_access table grants privileges 
  (either view, update or delete) to the node to anyone with that grant ID.

What the Grant ID really means is completely up to the realm that's using it. 
In the case of taxonomy access (which uses the term_access realm), a GID maps 
directly to an RID, which is a Role ID, and is one of the most common 
groupings. But for something like OG, the GID is a NID which points to the 
organic group node that represents the group. Other modules could have other 
ways to group users together.