table 50100 "Custom Table"
{
    DataClassification = CustomerContent;

    fields
    {
        field(1; "No."; Code[20]) { }
        field(2; Description; Text[100]) { }
    }

    keys
    {
        key(PK; "No.") { Clustered = true; }
    }
}

page 50100 "Custom Card"
{
    PageType = Card;
    SourceTable = "Custom Table";

    layout
    {
        area(Content)
        {
            group(General)
            {
                field("No."; Rec."No.") { }
                field(Description; Rec.Description) { }
            }
        }
    }
}

codeunit 50100 "Custom Logic"
{
    procedure ProcessRecord(var Rec: Record "Custom Table")
    begin
        // Business logic here
    end;
}