I checked the resources section here and found that there was not break down for the prefix/suffix tables as I thought there would be. Since someone asked me about this a couple of weeks ago I though I would list out part of my reply to them here also.For the first few columns.
version controls which version of the game the affix will work in. 0=for pre expansion items that are imported into the game when a character is imported. 1=is for D2C games or Lod games. 100= is for LoD games only.
spawnable will the affix be able to appear on items in the game or not. 1=yes, 0=no.
rare can the affix appear on rare or crafted items. 1=yes, 0=no.
level minimum alvl for the affix to appear on an item.
maxlevel maximum alvl that the affix will appear on an item.
levelreq minimum required level to use the item if this affix appear on the item. Other affixes or the item itself may raise the value.
classspecific what class can gain benefit from the affix (other classes can equip the item but are not able to use the affix).
class specifies a class and that class will use the level requirement in the next column instead of the normal level requirement for that affix.
classlevelreq The minimum required level to use of the affix by the class specified in the previous column. This overrides the value in levelreq for the indicated class.
frequency relative chance of that prefix spawning on item. To calculate the chance total up all the frequency numbers that can appear on the item (based on item type, alvl for the item, allowed groups) and this will be the total_frequency. Then the chance that the affix will appear will be frequency/total_frequency. This is handled separately for prefixes and suffixes.
group this is used to limit some of the affixes from appearing together. This is why you cannot get prefixes for +2 sorc skills and +3 lightning tab on the same item (both are group 125). When an item is generated the item cannot have more than one affix from the same group on it. Prefixes and suffixes share the same pool of group numbers. There currently is no overlap in group numbers between the prefix and suffix pool.
Skipping over the mods themselves.
itype1-7 these are the item types that the affix can appear on.
etypes1-3 these are the item types that are excluded from the affix appearing on.
Example 'Cruel' can appear on weapons but not on staffs, wands or orbs.
divide, multiply, add are used for calculating the price of an item (I do not have the formula). There are only a few listed in the affix table due to most of the values being pulled from the itemstatcost.txt file. The few that are listed are due to their not fitting the normal pattern of attributes (res-all is a mixture of the various resists).