Find a specific string format in a segment

Howdy,

I want to search a line of HL7 and find anything that reflects a specific format.

Like this:

#In this example the SSN is 011-22-3348

#I need to be able to find anything that matches a SSN format, store it to a variable and ultimately put it back in the message as xxx-xx-3348

#How does one scan, using TCL, to find a specific format?

#I have been sing the string scan $var1 $var2, but no luck yet.

PID|1||M000000115^^^YVMC.TEST5.66^MR^YVMC~011-22-3348^^^YVMC.TEST5.66^SS^YVMC