Here is /most/ of the columns explained. I will also be releasing lists for possible entries and what they do for each column
Entry- The entry ID
Class- Item quality
subclass- Things such as if its consumable or not.
Field4- Don't know
Name1- Name of the item
Displayid- what it looks like on the player
quality- item quality
Flags- don't know
buyprice- How much it costs in copper
sellprive- How much it sells for in copper
Inventorytype- What type of bag can it go into, or does it go in keyring.
Allowableclass- what class its specific too
Allowablerace- What races its specific too
itemlevel- The level of the item {not whats required to wear it}
requiredlevel- level required to epuip the item
Requiredskill- What skills are required to wear this
Requiredskillrank- rank required to wear highest being 350
Requiredfaction- What faction is needed to buy/equip item
requiredfactionstanding- what there rep has to me to use item
unique- is it unique
Maxcount- what does it stack too
containerslots- >than 0 and its a bag with that many slots
Stat_type1-10- what type of stat, 0 is none.
stat_value1-10- how muhc of that stat
dmg_min1-5- minimum damage
dmg_max-1-5- maximm damage
dmb_type1-5- what type of damage does it do? IE frost, shadow, physical.
armor- The amount of armor it has
fire/nature/frost/shadow/arcane res- how much resistance it gives to each magic type
ammo_type- ifs its ammo, what type
range- range of the items ability
spellid_1-10- does it have a spell{this includes most things like +mana regen/spell damage/healing.}
spelltrigger_1-5- What triggers this spell{on hit, when hit,always active}
spellcharges_1-5- How many charges does it have{0 is unlimited.}
spellcooldown_1-5- The cooldown on the spell {-1 means no cooldown}
spellcategory_1-5- Don't know, just leave it 0 :P
bonding- Bind on equip, bind on pickup, bind on use, don't bind.
discription- The gold text on an item.
quest_id- I think it means what quest does it start, if it starts one.
lock_id- Don't know
lock_material- don't know
SheathID- if its sheathable where does it sheath to
randomprop- Don't know
unk203_1-7- Don't know
block- whats its block value
itemset- What set is this item a part of
maxdurability- Whats its max durability
ZoneNameID- don't know
Mapid- Don't know
bagfamily- don't know
Totemcategory- Does it allow shammies use there totems?
socket_color_1-10- what color the socket is
Socket_bonus- Whats the socket bonus
gemproperties- If its a gem whats its properties
ReqDisenchantskill- whats the skill requirement to disenchant this item {-1 means it can't be disenchanted}
unk2- don't know.