Work item startDate attribute usage

While working on some custom work items (attributes and customized
editor presentations), we noticed a standard startDate attribute for
work items, however, it does not appear that any of the standard work
item types use it. At least, it does not seem to show up in any of the
editor presentations. Is it an internal attribute that has a special use
or are we free to add it to our editor presentation and do what we want
with it?

While working on some custom work items (attributes and customized
editor presentations), we noticed a standard startDate attribute for
work items, however, it does not appear that any of the standard work
item types use it. At least, it does not seem to show up in any of the
editor presentations. Is it an internal attribute that has a special
use or are we free to add it to our editor presentation and do what we
want with it?

This is an internal property, whose usage is reserved to schedule a work
item for a fixed start day, eg for next Monday morning.

However, after we implemented this feature, we were not happy with the
UI, the feature was not polished enough, and offering two different
scheduling modes seemed to be confusing. As we were late in the cycle,
we decided to remove the UI only.