WR is not wrong.
But we have special category as Mumbai Local.
Generally, news related to non-suburban trains are posted under CR / WR zone.
For EMUs ML is useful.. bcoz when we use advance search option to search news related to Mumbai locals, then this news will not appear. U can use 'advanced search' option & see what news are posted under ML...
more... category.
.
This is not rule. Its my suggestion only. :)