A kind of 'specification' for the IE game effects.
This description uses the IESDP effect structure definition with updates.

V1.0 effect struct (you need to convert it to V2 on the fly)
typedef struct {
  short feature; //opcode
  unsigned char target; //target type
  unsigned char power;  //level
  parameter par1;
  parameter par2;
  unsigned char timing; //timing method
  unsigned char resist; //resistance type
  long duration;  
  unsigned char prob2; //usually 100
  unsigned char prob1; //usually 0
  char resource[8];    //1. resource
  long count;
  long sides;
  long stype;
  long sbonus;
  long unknown2c; //unused in V1.0, but copied over to 2.0
} feat_block;

//effect body (V2.0 effects)
//please note that in an .eff file there is an additional header
//before these (the first 8 bytes are doubled)
Offset Size (data type) Description
0x0000 4 (char array) For on disk effects, this is a copy of the Signature field from the header. For embedded EFF V2.0 structures, this is zeroed out.
0x0004 4 (char array) For on disk effects, this is a copy of the Version field from the header. For embedded EFF V2.0 structures, this is zeroed out.
0x0008 4 (dword) Effect type
0x000c 4 (dword) Target type
0x0010 4 (dword) Power (level)
0x0014 4 (dword) NP1
0x0018 4 (dword) NP2
0x001c 4 (dword) Flags (timing method)
 0 - duration
 1 - permanent
 2 - while equipped (source of effect)
 3 - delayed duration (after delay duration)
 4 - delayed (after delay it is permanent)
 5 - special, delayed, unsaved
 6 - special, duration
 7 - special, ?
 8 - permanent, unsaved
 9 - permanent after death
 10 - trigger (just expired)

0x0020 4 (dword) Time (duration)
0x0024 2 (word) Probability 1
0x0026 2 (word) Probability 2
0x0028 8 (resref) resource
0x0030 4 (dword) die sides/max level
0x0034 4 (dword) dice count/min level
0x0038 4 (dword) save type (stype)
0x003c 4 (dword) save bonus (sbonus)
0x0040 4 (dword) Is Variable? (same as 0x2c in EFF V1.0)
0x0044 4 (dword) Spell School (used for dispelling)
0x0048 4*3 (dword) Unknown
0x0054 4 (dword) Resistance Type (resist)
0x0058 4 (dword) NP3
0x005c 4 (dword) NP4
0x0060 4*2 (dword) unknown
0x0068 8 (resref) VVC
0x0070 8 (resref) 3. resource
0x0078 4*2 (point) Source point
0x0080 4*2 (point) Target point
0x0088 4 (dword) Source type of effect (0 - none, 1 - item, 2 - spell)
0x008c 8 (resref) Source of Effect (used for equipping and dispelling)
0x0094 4 (dword) resource flags
0x0098 4 (dword) projectile
0x009c 4 (dword) item slot
0x00a0 32 (bytes) variable
0x00c0 4*2 (dword) unknown
0x00c8 4 (dword) Secondary Type (used for dispelling)
0x00cc 4*15 (dword) unknown


An effect's lifecycle:
(apply time)
1. Check if it affects the target
- if percentages don't match, drop it
- if level limits don't match, drop it (some effects don't have this)
- if resistable, check for resistance (once for an applied block)
- if saving throw applies, check for it (once for an applied block)
2. If it is a delayed effect
- precalculate the time of onset (in game time) (store it in the duration field).
- put it on the fx list
3. If it is an instant effect (some opcodes ignore delays, so they are always instant)

(in each update cycle in creatures)
1. copy the original stats to the modified stats
2. apply all effects in their original order
- if the effect isn't in time (delayed or delayed duration, 3 or 4), skip it
- if a delayed effect reached time: change it to permanent (i think this is a different permanent)
- if a delayed duration effect reached time: change it to duration
- if the effect is permanent (1 or 9), apply it (some effects couldn't be permanent, these effects just apply, then go away)
- if the effect reached end (duration), set a special timing method (10)
- if an effect reached expiration (10) remove it from the queue

(dispelling/removal)
There should be a way of:
1. Dispelling all by power level  ( remove all effects <= power level)
2. Dispelling all by source of effect ( remove all effects == soe)
3. Dispelling all or first that matches a spell school or secondary type
- there is a 'dispellable' flag in the effects which normally disables dispelling. But there should be a 'forced dispel' flag.
4  On death: remove all effects except (9)

(saving)
Effects that are not saved: 2 -'while equipped'

