4f339065_eference___The_Realm_Component__Description
[Attribute] userCredCol [Description] 
Name of the column, in the "users" table, which contains the user's credentials (i.e. password(. If a value for the digest attribute is specified, this component will assume that the passwords have been encoded with the specified algorithm. Otherwise, they will be assumed to be in clear text.
Apache Tomcat Configuration Reference - The Realm Component
Description