Design families often make use of shared parameter files because they have many advantages : they can be exchanged between colleagues, they have a GUID and they can serve as unique source within a company . On top of that, by manually editing the shared parameter file, we can make them invisible or not modifiable by users which is a good hidden feature as some parameters do not necessarily need to be visible or editable by users within a project. However, visible or not, editable or not, considering that they are shared parameters, they will always appear as schedulable in the schedule options.
One could turn a shared parameter into a family parameter to avoid this issue but one would lose all those upsides. So if some specific parameters are needed as shared ones, this creates non negligible issues because a family using too much shared parameters would bloat the available parameters for schedules and sometimes make things confusing and complicated in the management of projects, making the incriminating family troublesome.
The idea would be similarly, as the VISIBLE and USERMODIFIABLE states, to create a new one named SCHEDULABLE (or something else). That way by editing the shared parameter file, a user could decide whether or not a shared parameter could appear in schedules. That would help managing parameters far easier and make projects data cleaner IMO.
