17.6.1.0920
CMOVE>
c-move-up
STRING
 
( c-addr1 c-addr2 u -- )

If u is greater than zero, copy u consecutive characters from the data space starting at c-addr1 to that starting at c-addr2, proceeding character-by-character from higher addresses to lower addresses.

See:
17.6.1.0910 CMOVE, A.17.6.1.0920 CMOVE>.

Rationale:
If c-addr1 lies within the destination region (i.e., when c-addr1 is greater than or equal to c-addr2 and c-addr2 is less than the quantity c-addr1 u CHARS +), memory propagation occurs.

Assume a character string at address 100: "ABCD". Then after

100 DUP CHAR+ SWAP 3 CMOVE>

the string at address 100 is "DDDD".

See A.6.1.1900 MOVE.