Yes, that's basically correct. There are two manuals that deal with the issue:
HDv 268, dated 01.05.29, that says that there are three different kinds of Buntfarben-Anstrich: a) small dapples, in order to blend the piece into the surrounding b) large areas, in order to optically disrupt the piece's shape, and c) artist's application, which is a special case and not a standard pattern. Details on Buntfarben to be found in:
HDv 488, from 1926, Annex 4
Which list the colours, dark green, earth brown, and clay yellow, and says that black gauges of 1 to 3 cm can be used to separate the colours (but that this is not obligatory). Borders could be "solid" or "tattered" depending on the purose. No fixed pattern for certain vehicles existed.
Colours to be applied directly upon the anticorrosion primer, no base colour foreseen.
The HDv 268, however, knows nothing about RAL numbers (although the RAL system had been introduced in 1927).