Hello Viv.

Sorry it took so long to respond back, but i had to move this project aside for two other projects.

After a whole day of reading and testing and trying, i decided to back with your first suggestion (HasFlag()) - which seems to be the preferred method when you use .NET 4.

However it still does not work :-(

I am getting now the error:
"Message: Sys.WebForms.PageRequestManagerServerErrorException: Method 'Boolean IncludesCode(Int32)' has no supported translation to SQL."

here is how i have set this up:

' had to spread this - the UT compiler did not like that one
< F l a g s ()> _
Public Enum e_SecurityCodes
    DMS_Accounting_All = 2
    DMS_Accounting_AR = 4
    DMS_Accounting_AP = 8
    DMS_Accounting_PR = 16
    DMS_All = 32
    DMS_Client = 64
    DMS_HR_Employee = 128
    DMS_HR_Caregiver = 256
    DMS_HR_All = 512
End Enum

Module SecurityTest
' had to spread this - the UT compiler did not like that one
    < S y s t e m .Runtime.CompilerServices.Extension()> _
    Public Function IncludesCode(ByVal DocSecurityValue As Integer) As Boolean
        Dim sc As New e_SecurityCodes
        If sc.HasFlag(DirectCast(DocSecurityValue, e_SecurityCodes)) Then
            Return True
        End If
        Return False
    End Function
End Module

Partial Public Class _Default
   ...
   Protected Sub Search_Btn_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Search_Btn.Click, Search_Btn2.Click
      ...
        Dim db = New DataClassesDataContext()
        Dim result_0 =
                From col_Row In db.Masters, z In db.DocumentTypes
                Select
                    ListCol =
                        System.Convert.ToDateTime(col_Row.Doc_Dte).Month.ToString.PadLeft(2, "0") & "/" & 
                                         System.Convert.ToDateTime(col_Row.Doc_Dte).Day.ToString.PadLeft(2, "0") & "/" & 
                                         System.Convert.ToDateTime(col_Row.Doc_Dte).Year.ToString.Substring(2, 2) & " | " &
                        col_Row.Doc_Type_Level3.Trim.Substring(0, 28).PadRight(28, ".") & " | " &
                        col_Row.Resource_ID.ToString.Trim.Substring(0, 6).PadRight(6, ".") & " | " &
                        col_Row.Resource_First.Trim.Substring(0, 14).PadRight(14, ".") & " | " &
                        col_Row.Resource_Last.Trim.Substring(0, 15).PadRight(15, ".") & " | " &
                        col_Row.Vendor_Name.Trim.Substring(0, 19).PadRight(19, "."),
                       ...
                       Doc_Type_Level1 = col_Row.Doc_Type_Level1,
                       Doc_Type_Level2 = col_Row.Doc_Type_Level2,
                       Doc_Type_Level3 = col_Row.Doc_Type_Level3,
                       Type_Level1 = z.Type_Level1,
                       Type_Level2 = z.Type_Level2,
                       Type_Level3 = z.Type_Level3,
                       SecurityCode = z.SecurityCode
                  Order By Patient_Last

                  ...

                 result_0.ToList()

                 Dim result_Match =
                     (From x In result_0
                     Where IncludesCode(x.SecurityCode)
                     Select x).ToList()
   End Sub
End Class

My research tells me that that error means linq can not translate the function into a sql statement and the function (obviously) will not be available to sql when the sql-statment gets executed.

Do you have any other thoughts, suggestions?

Thank you for all your help!