= distribute_state_pdaf = The page document the user-supplied call-back routine `distribute_state_pdaf`. The routine `distribute_state_pdaf` (called `U_distribute_state` in the PDAF core routines) is a call-back routine that has to be provided by the user. `distribute_state_pdaf` is called by `PDAF_get_state` and `PDAF_assimilate_X` with 'X' being the name of a filter method. The interface is the following: