When SelectObject is called, the font mapper finds the closest match to the logical font. If application specifies DEFAULT_CHARSET (= don't care), and the matching result is the font that support more than one CharSet, the font mapper selects the following CharSet as the result.
ANSI_CHARSET
The Open32 NLS Extension saves the result Windows CharSet id of the matching font in the Open32 internal font object, to prepare for later references from applications.