pre-war german army warm under trousers-for drillich uniform?

[corporalSteiner]

interesting light cotton (not hbt) off-white trousers, nicely stamped 1919 i believe, with standard german army property and size markings, and loops to attach to the inside ties of service trousers. are these winter warm linings for drillich work trousers perhaps?
thanks in advance.

[corporalSteiner]

t2

[corporalSteiner]

t3

[corporalSteiner]

could anyone advise where this post may be best placed on the forum for firm response. thanks in advance.