Group Mode: Group Mode is used to associate linedefs and sectors in order to allow functions such as the remote activation of lifts, doors etc. In technical terms, it provides an easy way to manipulate the tag values of sectors and linedefs. An important setting in Hellmaker is the Inactive Group Tag value. This is just a tag number which is not used for any functions. By default it is zero, but it can be changed on the Preferences panel. The only time it may be necessary to change it is when editing a level made by someone else that uses a value of zero for a tag that does something. You can enter Group Mode by choosing Group from the Mode menu, or using the keyboard equivalent (command-G). When in group mode, only sectors and linedefs are visible. When you click on a sector or linedef, it is selected and all of the other sectors and linedefs in the same group (with the same tag number) become highlighted in a different colour. The group becomes the selected group.   To add a sector or linedef to the selected group, shift-click on the sector or linedef. Shift-clicking also removes sectors and linedefs from the selected group, and puts them into the inactive group. You cannot (directly) add to or remove from the inactive group. If you shift-click on anything while the inactive group is the selected group, an error message appears. To create a new group (with a new tag number), command-click on the first sector or linedef that you want to be in the group. A new tag number is assigned to the sector or linedef.