I have the following in my TDL template definition:

<[If IsPrimaryKey ]>[Key]<[EndIf]>
        <[If IsStringField ]>[Size(<[SourceColumnMaxLength]>)]
        [DbType("<[SourceColumnDbType]>(<[SourceColumnMaxLength]>)")]<[EndIf]>
        [Persistent("<[SourceColumnName]>")]<[ UserCodeRegion "AdditionalAttributes" ]>
        // __LLBLGENPRO_USER_CODE_REGION_START AdditionalAttributes
        // __LLBLGENPRO_USER_CODE_REGION_END
        <[EndUserCodeRegion]>
        public <[TypeOfField]> <[EntityFieldName]>
                ....

If I put code in between those region comment lines, it's erased on regeneration. Am I missing something obvious here?

Thanks!

Do you have more regions called 'AdditionalAttributes' in the template? FOr example, entity templates have that region at the top of the file. It's likely your region is overwritten with the contents of another region with the same name. So include the macro for the field in the name.

That solved it, thanks!