correcting some typo and adding quick frn affiliation

FCC_provider_list.qmd

@@ -12,7 +12,7 @@ engine: knitr
 source("R/table_with_options.R")
 ```
 
-The data set was downloaded the 26-04-2024 adn was apparently avaiable since 11-03-2024. 
+The data set was downloaded the 26-04-2024 and was apparently availiable since 11-03-2024. 
 
 A csv version of it is available in `data/`
 
@@ -57,5 +57,16 @@ knitr::kable(table(isp$Operation.Type))
 
 It seems `Affiliation` has the same number than `Provider.ID`. 
 
-Provider.ID is close but a bit less number than `FRN` whcih seems to be the unique identifier of this table. 
+`Provider.ID` is close but a bit less number than `FRN` which seems to be the "primary key" of this table.
+
+A quick check indicate that all `Provider.ID` are 6 characters (hence the one with 7 in FCC NBM is probably an error). `FRN` is also always 10 characters.
+
+# How FRN are split between Affiliations:
+
+```{r}
+FRN_by_affiliations <- sapply(split(isp$FRN, isp$Affiliation), function(x) length(unique(x)))
+FRN_by_affiliations.dat <- data.frame(Affiliations = names(FRN_by_affiliations), 
+                                      count_frn = FRN_by_affiliations)
+knitr::kable(table(FRN_by_affiliations.dat$count_frn))
+```