TOP loads automatically the categories. The module is Categories.arx and must be spread with the file "Categories.ini".

The main category’s tool is the management dialogue box: a list (similar to the parts tree) with the list of categories.

The dialogue is displayed when loading TOP. The system saves the display settings: if during the previous session the dialogue was closed, at the following the dialogue will remain closed.

When loading the programme, a default category with all graphical entities not included in any other category is created automatically. The category’s name is “:DEFAULT”. The dialogue displays the default category with a different background (yellow) to show the peculiarity of this category.

The default category can NOT be erased. The user can only rename it.