this will get you part way there.........
="SH-"&TEXT(MONTH(TODAY()),"00")&"-001"

Changing the 001 each month will have to be based on a frozen "standard"
somewhere, and this month will change if the file is created and saved and
opened sometime in the future........methinks what you are really wanting is
a custom "datestamp", which would be better served with VBA.

Vaya con Dios,
Chuck, CABGx3



"Jon" wrote in message
...
Hi,
I have a cell that I want to be a control number for documents. What I
want
to do is making this cell contains 3 difference data type e.g. SH-07-001
The SH is two letters, 07 is the current month and change by the beginning
of new month (automatically) and the 001 change by the new month (001+1)
Can any body help me please???