This script is meant to be run on the distributor in the distributor database as mentioned above.

I am using the sp_MSforeachDB stored procedure which takes a query as a parameter and runs it against each DB on the server.  The SQL that is being run against each database is in the @command variable.  That is the reason for the SQL in single quotes.

The ? will be replace by the database name as the sp_MSforeachDB cycles through each database on the server.  Then the rest of the SQL will be ran in that database.

Sorry if that was not clear.