Is null dependent on OS or locales?

[CortoMaltes]

I have a Access 97 application distributed throughout 17 countries European for cataloguing and indexing of publications. When users have completed a set of indexations for a given month, a VBA function allows for the export of that set; this export creates a fully tagged text file, by checking whether a field contains data (using IIf and IsNull) and, if so, creates the tagged line and moves on to the next field.
Even though most of the export files are perfect and tagged lines are created only when data exists, some others still create empty tagged lines. I have noticed that this is not happening randomly but with specific countries (e.g. France). However, I have not been able to be deterministic in what concerns the operating system under which the application is running...
So I'm trying to enquire whether there can be any relation between the check of nulls and the operating system or locales of the machine where the applications is running. As anybody ever experienced such a behaviour? Any hints or suggestions on how to check for nulls in a sure way? Thanks in advance.

 

[jgoodman00]

IsNull is the correct way to check for Null. Could these blank lines be create by the existence of zero-length strings?

I am wondering whether certain countries have special characters, unique to their language. In this case, perhaps the index files you receive contain these characters, but they are lost in the conversion to your keyboard code?

The MSDN library has some good documents concerning Null, & its use. I read a particularly good article in a SQL server book released by them... James Goodman