There are a couple of things you can do. IN general, however, I find it
easiest to throw exceptions up to the UI for problems and then parse the
exception there. It is very specific and does not require passing back
values.

Of course, you can also use enums.

public MyEnum TestValidation()
{

   if(failedOneValidation())
      return MyEnum.FailedOneValidation;
   if(failedTwoValidation())
      return MyEnum.FailedTwoValidation;

}

But, this is harder if you embed it down levels, which often happens in
tiered approaches. Exceptions can bubble all the way to the UI and be
handled there.

To make sure these validations are logged, you can use the new policy
injection block (part of EntLib 3.1). Then you can turn on or off items by
config.

a common approach popular in the java world is to use a rules engine
thats hosted by the business logic layer (JBoss, JxBRE, SRE, etc). this
layer can also pass info used to generate the page validators, so
validation logic is all in one place.

on sourceforge.net, along with the java source you can find some .net
ports. there are also commercial products.

-- bruce (sqlwork.com)