myDataSource.url = jdbc:mysql://db.domain.com/space
myDataSource.driver = org.gjt.mm.mysql.Driver
myDataSource.user = username
myDataSource.password = xyz

_db         = myDataSource
_table      = PERSON
_id         = ID

firstname   = FIRSTNAME
lastname    = LASTNAME
email       = EMAIL
createtime  = CREATETIME
modifytime  = MODIFYTIME

It seems a couple background facts about persistence should be mentioned here.
Perhaps obvious to old hands, but they should be documented explicitly.
(I'm just learning this myself, so hope this is correct...):

- How you choose between the two persistence layers:
Persistence is via either the embedded XML store or the RDMS ORM layer.
You choose which one by whether or not your create type.properties.

- Which objects are persisted?
HopObjects can be transient or persisted. As I understand it: You can create
transient HopObjects with "new" whenever you like, and this can be useful.
An object becomes persistent if it is becomes a property or a member of the child
collection of a object that's already persistent. Presumably, all persistent objects
then trace back up to root, the only initially persistent object.

This latter fact could be discussed more in the docs. (It seems there is one
sentence about it in the middle of the "conceptual overview", but not in the
introductions or tutorial.) Also, a paragraph or two on common uses of
transient objects (for instance, what about wrapping Java objects with
HopObjects so they can be skinned?) would be helpful.