CW controls in CW macros

Here is a list of macros that I implemented in a keyer once.  I chose '$' as the char to parse to start the macro except for the '*' for the first one.
*_____  concatenate chars until space or EOL (e.g. *SK )
$P_____ mS pause (e.g. $P1000 for 1 sec)
$R repeat
$M__ play msg (e.g. $M03 to play msg 3) if in the middle of a msg, orig msg continues
$C insert mycall. Implies need to easily set mycall
$N send next serial number. Implies need to easily reset serial to any value.
$S___ change speed
$SS Return speed to value before $S encountered (see above)

I would love to see something similar implemented in the Flex CWX strings.

73,
Len, KD0RC