If this field is non-null, and the current XTREE is in single-select mode, and the XTR.COLUMNACTIVE parameter is not zero, then the initial selection is established by searching the active column for the specified string (overriding the ANSWER parameter, which normally sets the initial selection). Note that:

•   SKEY does not require a trailing null

•   A match will succeed as long as the contents of SKEY matches the start of the data in the column (i.e. "Ab" will match "Abbey Road").

•   SKEY is not cleared or set by XTREE