World: r3wp

and then replace in situ.

leaving the whitespace unaffected.

in that case sorting them from long to short to begin with will foil 
recursive macro rxpansion

at  the macros and expansons single tokens

HTML/XML entities begin with & and end with ; for just this reason. 
What kind of text? can you give us an example?

well, the macros wiill end up being delimited by whitespace

Heart: Heart regular rate and rhythm, no rubs, murmurs, or gallops 
noted. 

A: Abdomen:  soft, nontender, no mass, no hernia, no guarding, no 
rebound tenderness, no ascites, non obese 
Hbp Hypertension (high blood pressure) #401.9.  
Ii Type II Diabetes #250.00

Are macros the only thing delimited by whitespace?

So, someone might type

heart:
A: with striae

macros are typed inside normal text.

That A: isn't delimited by whitespace.

it is .. it's preceded by a newline character

from the line above ...

Not it it were on the first line. Plus, is the : part of the macro?

True .. not if it were on the first line.  Some macros contain punctuation.

so, a: is a macro, whereas "a" is not.

the macros are user defined.

so, in the examples given above, the first word in each line is the 
macro.

Do they always contain the same punctuation, is the punctuation per-macro, 
of does it need to be factored out?

isn't there a controled vocabulary for this sort of thing

per macro.

Is a macro always the first word in a line?

what do you mean controlled vocabulary?

no, it can be anywhere in a line.

an ontology

Is there a seperate syntax for defining macros?

no, it's just a text file which is read in at start up.

the scenario is this guy uses these macros as he types up his notes. 
 his software currently expands them inline as he types.

So in use, a macro a: will always be a: in the text. Will it be A: 
sometimes, or "a:"?

I would have to intercept the keyboard handler to do this .. so I 
want to try and just do the replacement after he's finished typing.

macros won't be case sensitive.

but groups of people doing the sane thing dont use the same nacros? 
  they should

no, they don't use the same macros.

so, it's user specific.

personal shorthand

yes

hmm I am in the bussiness of sharing biological information and I 
got to say  please strongly consider  creating  an ontology if one 
does not exist already

Oh .. sure there's ontologies ....

but people don't use them when typing.

SNOMED CT is the one being currently promulgated

and there's the proprietary MEDCIN

so, personal shorthand should expand into a controlled vocab ideally

yes

Ii Type II Diabetes #250.00
here the macro expansion includes a code (CPT) from the AMA.

and the macros should  also be part of that  ontology

Medcin contains over 100,000 clinical propositions

no one is going to remember that!

Can you make sure that no whitespace sneaks into your macro names?

tom, I can't force the guy to change his macros!

no that is what browaers are for