The phase dates need not necessarily be always within season dates. This is because sometimes you may have items crossing seasons. For instance, sometimes you can have a transitional phase that bridges the two seasons. There are some items which transcend from ONE season to another and hence are associated to a phase which LIES in both seasons.

RMS only uses Season and PHASES as attributes or to do things such as create item lists and allows OVERLAPS because they have no CRITICAL functionality based on those seasons or phases.

The phase dates need not necessarily be always within season dates. This is because sometimes you may have items crossing seasons. For instance, sometimes you can have a transitional phase that bridges the two seasons. There are some items which transcend from one season to another and hence are associated to a phase which lies in both seasons.

RMS only uses Season and Phases as attributes or to do things such as create item lists and allows overlaps because they have no critical functionality based on those seasons or phases.