MAS90 API?

If you could get your in house system to export flat files, you could use the VI module to import it into MAS.  You can use a scheduler for this activity or launch it.  Customer balance lookup could be done with an Microsoft query.  You can connect throught the SOTA MAS odbc.
And then there is always custom programing.

Thanks for your informative reply. But I still have some questions:

Do  need the VI in order to create the Import?

Once created - you mention a scheduler - can it then be imported at every 30 minutes or so?

Any way to launch this Import from another (non-Mas90) program?  If not can the Import be triggered say by the presence of a file in a folder?

Will SOTAMAS work with Mas90? Where does one get this (I didn't find it on the Sage site)?

You do need the Visual Integrator Module to actually write to MAS90 Files.  I do believe you can schedule the Job to run through Windows Scheduler.  VI has a cycle function that you can also utilize to run the job from outside of MAS.

If you set up a query in Excel or Access, your souce would be from ODBC.  This driver is already on your workstations if you have MAS loaded.

There is an API. It is called Business Objects, although it is very carefully controlled by SAGE and not released to end users.

VI is certainly a possible method to use. You have not mentioned what external application has the additional information to merge into MAS90. It may be possible to use PERFORM LOGIC (MAS90 3.x and above) to combine the two systems data during an import. The VI end user solution can work, although can become complex depending on your resources.

So can one get this API?

The external app is an in house vb.net/sql app.

What is PERFORM LOGIC - is this a built in language for MAS90?

Yes. It is documented to Master Developers. Becomming one can be more dificult than getting a college education, but is the same. Classes, tests and money are required. It may not a good short term solution.

PERFORM LOGIC is part of VI. It is hooks into a VI job allowing ProvideX code to be used to extend the function of a VI JOB

So basically what I would need is VI. How is the documentation for PERFORM LOGIC and VI ?