The CHGC command changes the case of every letter in the specified
 number of entities: lowercase letters become uppercase and uppercase
 become lowercase.

 Format: [+|-][count]CHGC[+|-][count][+|-]entity

 CHGCSR (change case of select region) works differently:  If there is no
 select range and the cursor is in the search string, CHGCSR changes the
 case of every letter in the search string.  If there is no select range
 and the cursor is not in the search string, CHGCSR changes the case of
 the character under the cursor, if it is letter.  If the [count] field
 is two or more, CHGCSR ignores the search string condition.