A Proxy Field Never Links To An External Field Library

All proxy fields defined in a BT5 should link to the Field Library defined in this bt5.

Good Example:

Base_viewPDMFieldLibrary[my_view_mode_title]

-> Base_viewFieldLibrary[my_view_mode_title]
  -> ...

Bad Example:

ApparelComponent_view[my_title]

-> Base_viewApparelFieldLibrary[my_view_mode_title]
  -> Base_viewPDMFieldLibrary[my_view_mode_title]
    -> ...

ApparelComponent_view[my_title]

-> Base_viewPDMFieldLibrary[my_view_mode_title]
-> ...
  
erp5_project/PurchaseOrder_view[my_title]

-> erp5_trade/Base_viewTradeFieldLibrary[my_view_mode_title]

The only exeption is for surcharging the behaviour of a field library which is sometimes required. In this case, it is required to create another skin folder (following the convention [surcharged_context]_[original_skin_folder_name]) and an empty field library could be created to surcharge the original one.

Semantic field defined in a field library could link to Base_viewFieldLibrary.

Good Example::

In the erp5_project BT5: erp5_project_trade/PurchaseOrder_view[my_title]

-> erp5_project_trade/Base_viewTradeFieldLibrary[my_view_mode_title]
  -> erp5_trade/Base_viewTradeFieldLibrary[my_view_mode_title]