The "Timing" field is intended to record whether a record is due to a request from our clients (so-called "reactive" work), or something we have reason to believe our clients will want done (so-called "proactive" work).
It is currently determined when a record is created by comparing the requesters of the work with those who appear to be support staff, i.e. those who have read/write access to all of the work data. Requests that involve anyone who is not support staff is classified as "reactive". Otherwise it's proactive.
Whenever the priority of a record is changed to be "Upcoming Requests", the timing is set to "reactive". Whenever the priority of a record is changed to be "Upcoming Projects", the timing is set to "proactive".
Ideally the same term would be used for both internal and external display. The term "projects" was all we could think of originally for work that wasn't explicitly requested of us. The term "proactive" is better, as it encompasses more than classic "projects", instead identifying the reason for the work. Changing "projects" to "proactive" proved controversial, so it's been left as is, for now, when dealing with the priority field.
The choice of the name "timing" isn't considered very good. If you can think of better name, please suggest it.
The field value isn't 100% reliable, as it has to guess when a record is created via the "gripe" importer, which can start work at other than an "upcoming" priority.
There is currently no direct user interface to the field. It's changed (indirectly) by changing priority as described above.
When specifying this field in a customized sort or display, the name "timing" can be used.