The object item lists consist of a set of list entries, one for each column in a row.

Each object list entry contains the item number for the object, the object type (text, sprite etc.), the justification (left, right or centre, top, bottom or centre), a pointer to the actual object and a pointer to an action routine to be called when the object is hit.

Note that it is possible to have just one large object list, which is 'cut up' into rows by making each row list start pointer equal to the previous row list end pointer.

Name      Off Size      Description
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wdm_xjst  $00  Byte  Object x justification rule.
wdm_yjst  $01  Byte  Object y justification rule.
wdm_type  $02  Byte  Object type: 0 = text, 
                                  2 = sprite, 
                                  4 = blob, 
                                  6 = pattern.
wdm_skey  $03  Byte  Item selection keystroke. (Uppercased)
wdm_pobj  $04  Word  Pointer to item object.
wdm_item  $06  Word  Item number if this defines a menu object.
                     -1 if this defines an index list entry.
wdm_pact  $08  Word  Pointer to item action routine.
                     Zero if this defines an index list entry.
wdm.olen  $0A  n/a   Menu object / index list entry length.
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