What is the difference between "bin ... gewesen" and "war" in written language? Martin Rosenau's comment on the question tagged below alludes to rules governing the use of them in written language, though I haven't been able to find these rules yet.
"In official German language (literature or newspapers) there are rules when to use which of the two forms. However for most native speakers in 'everyday language' it depends on the region they come from if they prefer 'war' or 'ist gewesen'. There is no difference in the meaning."