To display some content in To-Do List, there must be first assigned a Smap3D P&ID project to the active assembly or its top-level assembly (that is for the typical case when a piping subassembly is opened in edit mode within the top-level assembly).
The information of the assigned project (including information on project pages taken into account) is stored in the respective assembly file, i.e. in the currently opened assembly or the respective top-level assembly (in case the active assembly is opened in edit mode within the top-level assembly).
When switching between assemblies in CAD, the content of To-Do List may change (according to the Smap3D P&ID project assigned to the active assembly).
The assignment can be removed by Tools menu Unassign P&ID project.
When assigning a P&ID project which contains more pages, it is possible
to define those which should be used and displayed in To-Do List with
Assign P&ID project 
.
The command can be used later for adding/removing pages to/from To-Do List.
The pages created in a Smap3D P&ID project later (after last assignment), are added in To-Do List automatically after refreshing (F5) or To-Do List reopening.
To-Do List can only
process normal
Smap3D P&ID project pages (i.e. those created with page function normal)
containing at least a line or a symbol.
Invisible lines (those with the Visible flag not set)
and lines with a name (Line Number) starting with IG_ are ignored (not
displayed in To-Do List).
To assign a P&ID project to an assembly, follow these steps:
from the P&ID To-Do List toolbar..
To unassign a Smap3D
P&ID project from an assembly just start Unassign P&ID project from
P&ID To-Do List toolbar (drop-down at button Assign P&ID Project
) and confirm the sequent message.
To add a newly created page to assigned Smap3D P&ID project to To-Do
List, simply start Refresh from P&ID
project 
or press F5.
To add/remove a page to/from To-Do List, follow these steps:
.