we can add new tags to the xml files, but without developer support they'll be useless. I wanted to post my suggestions, and anyone else can add their own thoughts. Ideally these will be 'relatively simple' to implement, but it's all relative

Weapons/Defense:
*min = minimum damage/absorbtion
*max = max damage
*mult = multiplier
combined: will allow damage rolls like, 1d6+3 (min=4, max = 9, mult =1) [treat old values as min=0, max=damage, mult=1]
firststrike = weapon fires and does damage before all others (except other firststrike weapons) - first round only

Tech:
*notrade = cannot trade this technology
*nosteal = cannot steal this tech
*uniquetorace = only the enumerated race(s) can research the tech

appending: if you want to add more to an already defined entry, use the same ID in your mod file
remove = allows a mod entry to remove the full entry (just a way to remove a predefined tech entry)

substitute = allows an entry to be substituted for another one, so that any references to that other entry are replaced by this one - followup technologies now require the substitute, as do weapons... allows easier modding support, with 'uniquetorace' you could have any entry be replaced by a unque one, but the rest of the tech tree would remain intact


Items:
*replaces = this item replaces another, so once it's available the other one(s) dissapear
- if an item is just shrinking in size or increasing in power, you can have it removed from the item list
uniquetorace = only the enumerated race(s) can build the weapon/item
- would allow a tech to open up different weapons for each race
substitute = same as (tech) above - you can replace laser II with your own version
remove = same as (tech) above - you can remove laser II

Improvements:
uniquetorace, substitute, remove...

the *'ed entries would be my first choices of what to add