A ``node program'' is the annotation you enter for a node. For computation nodes, it consists of a description of what variables the node uses and what subroutine it calls. A computation node's ``node subroutine'' is the text of the subroutine it calls.
If you click the right mouse button on a node, a text editor window that contains its node program will appear. If you shift-click the right mouse button on a computation node, a text editor window that contains the node subroutine will appear. Simply exit the editor normally (ZZ for vi) to make these windows go away. See the section on customizing HeNCE if you wish to use an editor other than ``vi'', the default.