class - How is non-standard worksheet.object created in this Excel VBA -

In the 2000 Excel 2000 code, VBA 6 - in a text that contains text boxes, combo boxes and buttons. TxtUsername is another, txtPassword - I inherited this code

 with  shtName. Absent "password" absent .range ("somenamedrange"). Value ends with code =  worksheet object > Sets a text value for  VBA Editor object list , but it is neither defined nor set up anywhere in the Excel project.  Options Explained  All Microsoft Excel is used on Object, Form and Module. I had said about worksheet objects that VBA editors in the worksheet object (e.g.,  
  private subtxtUsername_Change) end sub  
 
 any item 
 
 
 worksheet.TxtUsername 
 
 worksheet.TxtPassword 
 
 
 is not shown nor set as the named category. 
 The value of both objects is used only by the specific reference worksheet.TxtUsername.Text other places were used. After setting the text / these values ​​to the worksheet, the locals do not appear in the window. They are definitely used because asbestos uses these objects successfully. 
 
 Summary: I understand formName.txtUsername.Text (or .value). I do not understand an  worksheet object  that is not defined by code and does not start - only the bright idea was to export a worksheet and see it in a text editor For whether my ancestors created the "custom" worksheet object, the way in which defines "default property" in a class module - manually vi 
 
 
 
 Thanks. > 
 The worksheets that are part of Excel spreadsheets should not be done immediately, they are part of the workbook and are just "always there" if they are not visible to the user, but the project is visible in the browser, "ThisWorkbook "Section may contain some code that creates the sheet invisible (Visual = false) when launching a workbook.