get_acoustic_deployments(): is location_manager supposed to be free text?

[peterdesmet]

These are the values for location_manager (i.e. station_manager):

> get_acoustic_deployments() %>% distinct(station_manager)
# A tibble: 20 × 1
   station_manager                                                       
   <chr>                                                                      
 1  NA                                                                        
 2 ""                                                                         
 3 "7"                                                                        
 4 "Catherine Gutmann Roberts"                                                
 5 "Rechteroever, onderaan aan trap uitwatering, uit te lezen rond laag water"
 6 "8"                                                                        
 7 "Pedro Afonso"                                                             
 8 "6"                                                                        
 9 "1"                                                                        
10 "4"                                                                        
11 "Jolien Goossens"                                                          
12 "2"                                                                        
13 "Eneko Aspillaga"                                                          
14 "Alexandre Alonso-Fernandez"                                               
15 "Pieterjan Verhelst"                                                       
16 "Emma Nolan"                                                               
17 "Bernardo Quintella"                                                       
18 "SARTI-upc"                                                                
19 "5"                                                                        
20 "LifeWatch" 

Some values are free text, other numbers: are these referring to an identifier? Should free text be allowed?