This example moves the start position of the selection backward through the document while the space character is found.
Selection.MoveStartWhile Cset:=" ", Count:=wdBackward
This example moves the start position of the selection backward through the document while Count is less than or equal to 10 and any letter from "a" through "h" is found.
Selection.MoveStartWhile Cset:="abcdefgh", Count:=-10