This is reflected by the way the credit is displayed. When the attribute is meant to indicate the film's current production status, it's listed immediately after the title and is displayed in red italics, like this:
Hulk, The (2003) (post-production) (technical supervisor)
If we want to indicate that someone worked as a post-production technical supervisor, their credit will instead appear like this:
Hulk, The (2003) (technical supervisor: post-production)
Note that the first type of attribute changes over time, while the second
doesn't. In other words, as soon as the film is completed or released, the
post-production attribute will disappear and won't be displayed next
to the title anymore.