Why region definitions behave differently in 2.7

[IoannesBarbarus]

Just discovered something that may be useful to someone else. There was an undocumented change in how duchy references in geographical_regions.txt are interpreted. At the time I just papered over the issue but I've figured out the cause.

Before, duchies equated to their de jure counties in landed_titles. Now, they equate to their de jure counties as of the start_date in common/defines.txt.

This only has any effect if you change the de jure liege of counties in history before that start_date. (Vanilla never does that at any time, but it has been possible and save-persistent since Horse Lords or around then.)

 

[IoannesBarbarus]

Correction: vanilla does change the de jure lieges of counties in the history files. It does this to c_gotland (under d_gotland 1161-1285), which is unaffected by this issue. But it also does it to c_hereford, c_powys, and c_shrewsbury, moving all of them out of d_powys for starts after 769.

This means that since 2.7, in regions, d_gwynedd and d_hereford now equate to their larger area visible in 1066, and d_powys equates to no counties at all.

EDIT: Another note... it used to be that it was buggy or crashy to have a titular duchy in your region definition. This doesn't seem to be the case anymore. It just has no effect.