To give full credit, the following is based on the Eamon Deluxe documentation.
This important information has changed in Eamon CS 3.0.0 and is reprinted here
in hopes it will be useful.

4.4    ARTIFACT TYPES

There are 17 types of recognized artifacts. You are also allowed to enter a
value of 17, 18, or 19 for your own special types.  All USER types are treated
as type 1 by Eamon CS unless you add your own code. Creating new artifact
types is very uncommon as most any type you'll need is already pre-programmed
and it is strongly suggested that you stay within the usual types. The types
are as follows:

 Type                 Format    Type                  Format
 ---------------------------    ----------------------------
  0. Gold...............0       10. Readable.............5
  1. Treasure...........0       11. Door/Gate............6
  2. Weapon.............1       12. Edible...............4
  3. Magic Weapon.......1       13. Bound Monster........7 
  4. In Container.......2A      14. Wearable.............8
  5. On Container.......2B      15. Disguised Monster....9
  6. Under Container....2B      16. Dead body............10
  7. Behind Container...2B      17. Undefined, User......0
  8. Lightable..........3       18. Undefined, User......0
  9. Drinkable..........4       19. Undefined, User......0

All of the formats have the same information in the Artifact object, including
Value, Weight, Location, etc.  The Type and remaining format fields are stored
in one or more ArtifactCategory objects, referenced by the Artifact.  Format #0
is all USER fields, the rest of the format fields 1-5 contain the following.

  Format 1             Format 2A              Format 2B
1-Weapon Odds        1-Key No.              1-(USER #1)
2-Weapon Type        2-Open/Closed(1/0)     2-(USER #2)
3-# of Dice          3-Max weight held      3-Max weight held
4-# of Dice Sides    4-Max items held       4-Max items held
5-# Hands required   5-Display Code^        5-Display Code^

  Format 3             Format 4               Format 5
1-Light Counter      1-# of Heal Points     1-1st Effect
2-(USER #2)          2-# of Drinks/Bites    2-# of Effects
3-(USER #3)          3-Open/Closed(1/0)     3-Open/Closed(1/0)
4-(USER #4)          4-(USER #4)            4-(USER #4)
5-(USER #5)          5-(USER #5)            5-(USER #5)

  Format 6             Format 7               Format 8
1-Room Beyond        1-Monster #            1-Armor Class
2-Key #              2-Key #                2-Armor Type
3-Open/Closed(0/1)   3-Guard #              3-(USER #3)
4-Hidden?            4-(USER #4)            4-(USER #4)
5-(USER #5)          5-(USER #5)            5-(USER #5)

  Format 9             Format 10
1-Monster #          1-'Takeable' status*
2-1st Effect         2-(USER #2)
3-# of Effects       3-(USER #3)
4-(USER #4)          4-(USER #4)
5-(USER #5)          5-(USER #5)

^ -- Controls display of container contents in all lists.  Example:  You also
     notice a mountain backpack [with "???" inside it].  Without special programming,
     this behavior occurs for In Containers only when they are open.  For Display Code 3,
     the GetMaxContentsNameListCount method controls the number of allowed content list
     names; beyond that, the system will use "something"/"some stuff".

                        Contents Artifact Count
  Display Code            1                > 1
  ------------     ---------------   ---------------
       0           [None/Disabled]   [None/Disabled]
       1           "something"       "some stuff"
       2           [Artifact Name]   "some stuff"
       3           [Artifact Name]   [Artifact Name List]

* -- 0=Can't be taken, 1=Can be. Should ALWAYS be 0 unless the body serves some
     sort of special function (such as collecting rewards, etc.).