MUMPS Address Validation

Question

I am working on prerequisite questions for a class I am trying to attend. I am working on revisions to two pieces of code. I have completed one and I am stuck on this one. I am trying to read an abbreviated address line. In this case FL33606. I am able to read the address. But I am receiving an undefined error for the Quit command "Q: done". Would someone be able to assist me in identifying what is wrong?

N prompt,val, done
    S prompt="Enter State and Zip (StateZip): "
    F  W !,prompt R val Q:val=""  D  Q:done  
    . I val'="?2A5N" W !,"Invalid entry" Q
    . S done=1
    I val="" q
    W !,"Valid Entry: ",val
    Q

Answer 1

I have two errors

• done variable should be defined before the first read
• the pattern should not be in quotes, where ? is the operator not =

  S prompt="Enter State and Zip (StateZip): "
  S done=0
  F  W !,prompt R val Q:val=""  D  Q:done  
  . I val'?2A5N W !,"Invalid entry" Q
  . S done=1
  I val="" q
  W !,"Valid Entry: ",val
  Q

Why do you use short commands, and dots?

Is not this much better readable?

  Set prompt = "Enter State and Zip (StateZip): "
  For {
    Write !,prompt 
    Read val 
    Quit:val=""  
    Quit:val?2A5N
    Write !,"Invalid entry" 
  } 
  If val="" Quit 
  Write !,"Valid Entry: ",val
  Quit

Answer 2

the short commands are legacy from when original MUMPS code and source were limited to 4K bits of memory.

the dots under the IF or i designate the steps for the given IF STATEMENT TO DO
more from the M or Cache language derivatives