http://bugs.winehq.org/show_bug.cgi?id=19176
--- Comment #3 from Per Christian Henden perchrh-wine@pvv.org 2009-07-04 13:36:17 --- I did some research, hope it can be useful:
A web search says WINANSI is Windows code page 1252, a superset of ISO 8859-1. And that they have replaced the control characters with letters.
Also, Google shows logs with this error occuring for the codepages 437, 850 and 852. The lower half of these three 8 bit tables are equal to the ansi table.
If these three (and other) encodings are subsets of WINANSI (disregarding control characters), then they could all be mapped to WINANSI. Perhaps that is what Windows' implementation of the WDML_CreateString is doing. The mapping operation may be simple: for every byte > 127, replace with value from convertion table.