Just a little note here that we noticed testing something (how it had not occurred before, I do not know).  We have a function that we were referencing from a referenced assembly that would format values to the slightly odd format being used by the ERP that we were talking too.  In  most cases it seamed to work OK, but for smaller values it didn't quite product the result we expected.

It turns out that the result of the Division functiod in BizTalk Server 2006 is a double.  The mapper being the way it is converts this to a string (assumably using .ToString()).  At least this is how it looks when I point ildasm.exe at Microsoft.BizTalk.BaseFunctoids.dll.

Now, rather simply put, I was being a fool and trying to convert this to a decimal and wondering what was going on.  I was passing what I though was a value of "0.00002" to my referenced method and expecting it to be formatted properly.  When we looked deeper in to the issue, we noticed that the value coming out was in fact "2E-05", which is how a float or a double would represent the value 0.00002.

Quick use of the double.TryParse() fixes this issue and off we trundle.

Worth keeping in mind, and also worth having a look at the base functoids using ildasm.exe when relying on their output.