Working with the Database - eXist: A NoSQL Database and Application Development Platform - page 90

After creation, you can change the Internet media type of a resource program‐
matically. However, you can't turn a non-XML resource into an XML one, or
vice versa.
Collections do not have an Internet media type.
The Internet media type of a resource (when not set explicitly) is
determined from the configuration file $EXIST_HOME/mime-
types.xml . This file maps file extensions to Internet media types (or
MIME types, as they used to be known) and tells eXist when to
treat a file as XML instead of binary data.
Created and Last Modified
Resource have both created and last modification date and time, however collec‐
tions only have a created date and time.
Owner, Group, Base Permissions, and Access Control List
The security settings for this resource. Find more information about this in
Chapter 8 .
System Collections
The database's collection /db/system contains eXist system-specific information.
Most of the information underneath this collection is maintained by eXist itself and
there is usually no need for a “normal” user to access it, because there are extension
functions for this.
For instance, in /db/system/security/exist/accounts you'll find user information, and
by querying the resources found there you could create a list of registered users and
the user groups they participate in. However, we definitely advise against doing this!
eXist does not guarantee that these files nor the format of their content will remain
stable in the future. Rather, this is internal configuration information and as such is
potentially subject to change without notice whenever a new version of eXist is
released. The preferred alternative is to instead use the appropriate functions from
the Security Manager and/or the xmldb extension modules, which should remain sta‐
ble.
There is one important exception to this rule: the /db/system/config collection must
be used to configure important properties for collections such as: indexes, triggers,
and validation. Underneath /db/system/config you'll find a partial copy of the data‐
base's collection structure with collection.xconf resources in some of them. We'll give
you more information about this in the chapters to come.