[EU4 YAML]: Determine Purpose of Integer following some keys

[modcap]

 WEACCGRANTELECTORATE_1:0 "Electorate Accepted"
 WEACCGRANTELECTORATE_2:0 "We accepted $ACTOR$ offer,"
 WEACCGRANTELECTORATE_3:2 "and are now an Elector in the Empire."

 HUMILIATE_ROTW_WAR_NAME:0 "$ORDER$$FIRST$ Humiliation of $SECOND_NAME$"
 NO_PROVS: "Cannot be used to take any provinces."
 blockade_ports:0 "Blockade ports"

In the base game localisation files, the vast majority of localisation strings have an integer following the colon separating the key from the value. Sometimes the integer value varies, and other times it is not present at all. This value does not appear to be a part of the YAML specifications.

Goal

Determine under what circumstances this integer is necessary, and what the value means.

[modcap]

Asked in Quick Questions Thread.

Update: Only one response, did not answer.