These are the attributes which all entities have. This is an explanation of the type 
'edict_t'. Attributes are referenced by the format 'entity_name->attribute'  (eg self->angle)

Many of these will be familiar to QuakeC programers.

NOTE - Not all of these are relevant to all entities (infact there are no entities
for which all of these are relevant). 

name              type              notes

absmin, absmax    vec3_t            position of min and max points of entity 
                                    relative to the world's origin
accel             float             acceleration of platforms
activator         edict_t *         entity which activated the current entity
air_finished      float             time when air will run out (when underwater)
angle             float             entity yaw set by level editor (-1 = up; -2 = down)
area              link_t            ?
areanum, areanum2 int               area where you currently are used when 
                                    checking if monsters can hear sounds
attenuation       float             attenuation of above sound (set at level edit)
avelocity         vec3_t            angular velocity (see note for velocity)
blocked           void              function to call when blocked? (optional)
chain             editc_t *         used when creating a list of entities
classname         char *            type of entity (eg 'player','monster_soldier')
client            struct gclient_s* points to the player controling it, NULL
                                    if not player controled
clipmask          int               type of objects the entity will not pass through 
                                    can be any of MASK_* or CONTENTS_* listed at bottom
                                    of this document
clusternums[]     int               ?
combattarget      char *            name of entity to attack (used once)
count             int               general purpose 'amount' variable, often set in level editor
damage_debounce_time    float       time when lava/slime can do more damage to player
deadflag          int               state of deadness :
                                    DEAD_NO, DEAD_DYING, DEAD_DEAD, DEAD_RESPAWNABLE
deathtarget       char *            name of entity to use when current entity dies
decel             float             deceleration of platforms
delay             float             time between triggering switch and effect activating
die               void              function to call when health <= 0 (MUST be present if the 
                                    entity can take damage)
dmg               int               damage done by entity
dmg_radius        float             area to do radius damage
enemy             edict_t *         entity to attack
flags             int               various attributes :
                                    FL_FLY            -flying
                                    FL_SWIM           -swimming, won't drown
                                    FL_IMMUNE_LASER   -not hurt by laser
                                    FL_INWATER        -set when entering water, cleared when
                                                       leaving
                                    FL_GODMODE        -god-mode on
                                    FL_NOTARGET       -will not be targeted by monsters
                                    FL_IMMUNE_SLIME   -not hurt by slime
                                    FL_IMMUNE_LAVA    -not hurt by lava
                                    FL_PARTIAL_GROUND -ground pulled out from under monster
                                    FL_WATERJUMP      -player jumping from water
                                    FL_TEAMSLAVE      -not first member of a team
                                    FL_NO_KNOCKBACK   -entity not thrown back by damage
                                    FL_POWER_ARMOR    -active power armor
                                    FL_RESPAWN        -entity waiting before re-spawning
fly_sound_debounce_time float       used with looping sound when pushing player (in_trigger.c)
freetime          float             time when entity was freed-up in memory
gib_health        int               health at which to gib :)
goalentity        edict_t *         entity currently moving towards
gravity           float             not used by any entites, but can be used to define reduced/
                                    increased gravity for individual entities (normal=1.0)
groundentity      edict_t *         what the entity is standing on 
groundentity_linkcount  int         used in conjunction with linkcount to see if the current 
                                    entity is still standing on the groundentity
headnode          int               ?
health            int               health of entity, increased and set in many places, but 
                                    should only be reduced by t_damage()
ideal_yaw         float             yaw the entity wants to face
inuse             qboolean          the entity exists in the world
item              gitem_t *         info about item (see below)
killtarget        char *            name of entity to remove when current entity triggered
last_move_time    float             time to play earthquake sound again
light_level       int               player's light level, used by monsters when checking if
                                    player can be seen
linkcount         int               changed by the gi.linkentity function ?
map               char *            filename of the next map, part of entity target_changelevel
mass              int               used when pushing entites and calculating knock-back for 
                                    weapons (eg rocket hits)
max_health        int               maximum health
message           char *            message when entity activated (set by level editor)
mins, maxs        vec3_t            position of min and max points of entity 
                                    relative to its origin
model             char *            filename of entitie's model
monsterinfo       monsterinfo_t     info about the monster (see below)
move_angles       vec3_t            the angle that the gun turret is facing
move_origin       vec3_t            the origin of the gun turret
movedir           vec3_t            direction currently moving in
moveinfo          moveinfo_t        used by the ships flying overhead
movetarget        edict_t *         entity to wark towards when not got anything better to do
                                    (such as killing the player)
movetype          int               how the entity moves :
                                    MOVETYPE_NONE     -never moves
                                    MOVETYPE_NOCLIP   -ignores walls, entities, etc.
                                    MOVETYPE_PUSH     -ignores walls, pushes entities
                                    MOVETYPE_STOP     -ignores walls, stops on entities
                                    MOVETYPE_WALK     -affected by gravity
                                    MOVETYPE_STEP     -gravity, special edge handling, 
                                                       used by monsters
                                    MOVETYPE_FLY      -no gravity, used by flying monsters
                                    MOVETYPE_TOSS     -gravity, hits ground and stops
                                    MOVETYPE_FLYMISSILE     -weapons, extra clip size when 
                                                             hitting monsters
                                    MOVETYPE_BOUNCE   -bounces (eg grenade)
mynoise,mynoise2  edict_t *         spawned when player makes a noise, monsters can home in on
                                    them
nextthink         float             time at which entity should call function 'ent->think'
noise_index       int               index of sound to play when entity is triggered
noise_index2      int               not used anywhere
num_clusters      int               ?
oldenemy          edict_t *         player they were attacking before distracted (by anither 
                                    monster hitting them)
pain              void              function to call when hurt (optional)
pain_debounce_time      float       prevent pain sounds/anims playing to often
pathtarget        char *            name of entity to move towards
pos1              vec3_t            top position of lift
pos2              vec3_t            bottom position of lift
powerarmor_time   float             time to stop showing translucent shield effects
prethink          void              function to call before each frame (optional)
owner             edict_t *         usually the entity that spawned this entity (eg 
                                    bullet is 'owned' by the monster that fired it)
radius_dmg        int               amount of radius damage done by entity
random            float             used to add a bit of time variation to func_timer
s                 entity_state_t    has several subtypes (see below)
show_hostile      qboolean          any monsters seeing this one will inherit its enemy
size              vec3_t            size of entity (vector from mins to maxs)
solid             solid_t           solidity of entity : 
                                    SOLID_NOT   -no interaction with other objects
                                    SOLID_TOUCH -touch inside after moving (used for
                                                 triggers)
                                    SOLID_BBOX  -touch on side (monsters, etc)
                                    SOLID_BDP   -bsp clip, touch on edge (for solid
                                                 walls, blocks, etc)
sounds            int               type of sounds to play - used by doors, lifts, etc
spawnflags        int               set by level editor, some values are :SPAWNFLAG_NOT_EASY, 
                                    SPAWNFLAG_NOT_MEDIUM, SPAWNFLAG_NOT_HARD,
                                    SPAWNFLAG_NOT_DEATHMATCH, SPAWNFLAG_NOT_COOP
                                    There are other possible settings, which I have not yet 
                                    looked at in detail.
speed             float             speed of misc entities, including moving buttons, the
                                    gun turret and the fly-by ships
style             int               type of entities (eg type of health box) also used as 
                                    areaportal number (something to do with separating areas)
svflags           int               either : SVF_NOCLIENT - don't send to clients
                                          SVF_DEADMONSTER - a dead monster
                                          SVF_MONSTER     - same, a bit earlier
takedamgage       int               can the entity be damaged? :
                                    DAMAGE_NO   -will not take damage
                                    DAMAGE_YES  -will take damage
                                    DAMAGE_AIM  -will take damage + weapons 'auto-aim' at it
target            char *            name of entity to trigger or move towards
target_ent        editc_t *         entity that platform/lift is moving towards
targetname        char *            name pointed to by target
team              char *            name of team which entity is part of
teamchain         edict_t *         the next entity in the team
teammaster        edict_t *         the master entity in the team
teleport_time     float             time when monster teleported into level
think             void              sets the function that should be called at time nextthink
timestamp         float             used by various functions to mark the spawn time of an
                                    entity or the start of a change (eg a light ramp)
touch             void              function to call when it touches another entity/the world
                                    (optional)
touch_debounce_time     float       prevent touch function from being called again too quickly
use               void              function to call when used (optional)
viewheight        int               height above origin where eyes are found
velocity          vec3_t            current velocity. I think this is used in the external
                                    c code to change the entity's position. Can anyone confirm
                                    whether this is internal or external?
volume            float             volume when playing above sound (set at level edit)
wait              float             time to wait before platform moves to the next point on its
                                    path
waterlevel        int               height of liquid : 
                                    0 - not in liquid
                                    1 - feet in liquid
                                    2 - on surface of liquid
                                    3 - surrounded by liquid
watertype         int               type of water the entity is in (see the CONTENTS_* list
                                    at bottom of document)
yaw_speed         float             speed to turn towards ideal yaw


gitem_t

referenced by 'entity_name->item.attribute'

Name              Type              Notes

ammo              char *            type of ammo to use
classname         char *            name when spawning it
count_width       int               number of digits to display by icon
drop              void              function called when entity dropped
flags             int               type of pickup :
                                    IT_WEAPON, IT_AMMO, IT_ARMOR
icon              char *            filename of icon
info              void *            ? unused
pickup            qboolean          function called when entity picked up
pickup_name       char *            displayed onscreen when item picked up
pickup_sound      char *            filename of sound to play when picked up
precaches         char *            string containing all models, sounds etc. needed by this
                                    item
quantity          int               ammo gained by item/ammo used per shot by item
tag               int               ? unused
use               void              function called when entity used
view_model        char *            filename of model when being held
weaponthink       void              unused function
world_model       char *            filename of model when item is sitting on level
world_model_flags int               copied to 'ent->s.effects' (see s.effects for values)


monsterinfo_t

referenced by 'entity_name->monsterinfo.attribute'

Name              Type              Notes

aiflags           int               controls how the monster will behave :
                                    AI_STAND_GROUND         -don't move
                                    AI_TEMP_STAND_GROUND    -stand ground for a short time
                                                             (don't get too close to enemy?)
                                    AI_SOUND_TARGET         -look for source of a sound
                                    AI_LOST_SIGHT           -just lost sight of player
                                    AI_PURSUIT_LAST_SEEN    -
                                    AI_PURSUE_NEXT          -able to get to last sighting point
                                                             this frame
                                    AI_PURSUE_TEMP          -continue to persue for a bit
                                    AI_HOLD_FRAME           -entity will hold the same frame
                                                             (eg machine gun firing)
                                    AI_GOOD_GUY             -don't attack you (prisoners)
                                    AI_BRUTAL               -keep attacking until enemy's 
                                                             health < -80 (usualy stop at 0)
                                    AI_NOSTEP               -used by exploding box
                                    AI_DUKED                -monster's (pathetic) attempts to 
                                                             evade your shots
                                    AI_COMBAT_POINT         -ignores everything else until it
                                                             reaches it's destination
                                    AI_MEDIC                -healing something (stop when the
                                                             'enemy's health > 0 )
                                    AI_RESURRECTING         -it's ALIVE!!! (almost) show 
                                                             resurection effects
attack_finished   float             time when attack will be finished (prevents further attacks
                                    before monster is ready)
attack_state      int               attack method the monster is using :
                                    AS_STRAIGHT       -moving forwards to firing position
                                    AS_SLIDING        -moving sideways to firing position
                                    AS_MELEE          -close range attack
                                    AS_MISSILE        -long range attack
currentmove       mmove_t *         current set of frames cycling between
idle_time         float             time until which the idle animation should be played
last_sighting     vec3_t            last point where the player was seen
lefty             int               if and attack_state is AS_SLIDING, the monster will go left
                                    otherwise it'll go right. this is swapped each time
linkcount         int               changed by gi.linkentity?
nextframe         int               next frame to display
pausetime         float             time to stop at a particular path_corner
power_armor_power int               energy the armor has left
power_armor_type  int               type of power armor:
                                    POWER_ARMOR_NONE, POWER_ARMOR_SCREEN, POWER_ARMOR_SHIELD          2
saved_goal        vec3_t            if the monster can't get to where it wants to this frame,
                                    that position is saved here
scale             float             adjusts the running speed of the monster
search_time       float             time to keep looking for player
trail_time        float             timestamp of last section of player's trail found

The following functions are called when certain conditions are met:

attack            void              ranged attack (optional)
checkattack       qboolean          function called to see if the monster will attack this frame
dodge             void              !!INCOMING!! so just duck 'cos they wouldn't aim for your 
                                    feet, would they? (optional)
idle              void              animation to 'spice up' the standing around (optional)
melee             void              close-up attack (optional)
run               void              has an enemy, getting ready to attack
search            void              searching for player animation (optional)
sight             void              just spotted someone (optional)
stand             void              function to call when just standing around
walk              void              moving towards movetarget

entity_state_t

attributes here are referenced by 'entity_name->s.attribute'

Name              Type              Notes

angles            vec3_t            angles of the entity :
                                    ...angles[0] = pitch
                                    ...angles[1] = yaw
                                    ...angles[2] = roll (not really used)
frame             int               current frame
effects           int               special effects to apply to entity can be one or more of:
                                    EF_ROTATE         -rotates (bonus items)
                                    EF_GIB            -leave a blood trail
                                    EF_BLASTER        -coloured light + trail
                                    EF_ROCKET         -coloured light + trail
                                    EF_GRENADE        -smoke trail?
                                    EF_HYPERBLASTER   -light + trail
                                    EF_BFG            -light + particles?
                                    EF_COLOR_SHELL    -coloured glow around the entity
                                    EF_POWERSCREEN    -green screen
                                    EF_ANIM01         -automatically cycle between frames 0 and 1 at 2 hz
                                    EF_ANIM23         -automatically cycle between frames 2 and 3 at 2 hz
                                    EF_ANIM_ALL       -automatically cycle through all frames at 2hz
                                    EF_ANIM_ALLFAST   -automatically cycle through all frames at 10hz
                                    EF_FLIES          -flies effect
                                    EF_QUAD           -quad damage 'glow'
                                    EF_PENT           -invincibility 'glow'
event             int               effects that last one frame :
                                    EV_NONE           -no effect
                                    EV_ITEM_RESPAWN   -item respawning
                                    EV_FOOTSTEP       -footstep noise
                                    EV_FALLSHORT      -noise from small fall
                                    EV_MALE_FALL      -noise from male falling
                                    EV_MALE_FALLFAR   -noise from male falling a long way
                                    EV_FEMALE_FALL    -noise from female falling 
                                    EV_FEMALE_FALLFAR -noise from female falling a long way
                                    EV_PLAYER_TELEPORT-teleportation effects
modelindex        int               index of precached model
modelindex2       int               for when one modelindex just isn't enough ;). Used with
                                    the final 2-stage boss (oops, sorry if that's a spolier)
                                    and to show separate player weapons
modelindex3,4     int               not used 
number            int               entity index number
old_origin        vec3_t            last position of entity (used in a few odd places)
origin            vec3_t            origin of the entity
renderfx          int               various drawing effects :
                                    RF_MINLIGHT       -can always see the entity
                                    RF_VIEWERMODEL    -don't let the player see this (himself)
                                    RF_WEAPONMODEL    -only let the current player see this
                                    RF_FULLBRIGHT     -entity always fully lit
                                    RF_DEPTHHACK      -for view weapon Z crunching  (?!)
                                    RF_TRANSLUCENT    -entity is see through
                                    RF_FRAMELERP      -? used by monsters and bodies
                                    RF_BEAM           -laser beam
                                    RF_CUSTOMSKIN     -skin is an index in image_precache
                                    RF_GLOW           -pulse lighting for bonus items
                                    RF_SHELL_RED      -red glow, when monsters are resurrecting
                                    RF_SHELL_GREEN    -green glow, from power shield
                                    RF_SHELL_BLUE     -blue glow, not currently used
skinnum           int               current skin number
solid             int               set by gi.linkentity, for client-side prediction
sound             int               to gaurentee shut-off of looping sounds




CONTENTS_SOLID          solid wall (not windows)
CONTENTS_WINDOW         windows
CONTENTS_AUX            ?
CONTENTS_LAVA           err.. lava
CONTENTS_SLIME          slime
CONTENTS_WATER          water
CONTENTS_MIST           !!Unused!! 
LAST_VISIBLE_CONTENTS   ?
CONTENTS_AREAPORTAL     portals to conserve memory used in map designing, also dont allow sounds to pass //kami0
CONTENTS_PLAYERCLIP     brush which player may not pass through //kami0
CONTENTS_MONSTERCLIP    brush where monsters may not pass through //kami0
CONTENTS_CURRENT_0      flowing current moving at angle 0 //kami0
CONTENTS_CURRENT_90     flowing current moving at angle 90 //kami0
CONTENTS_CURRENT_180    flowing current moving at angle 180 //kami0
CONTENTS_CURRENT_270    flowing current moving at angle 270 //kami0
CONTENTS_CURRENT_UP     flowing current moving up //kami0
CONTENTS_CURRENT_DOWN   flowing current moving down //kami0
CONTENTS_ORIGIN         used for rotation, invisible //kami0
CONTENTS_MONSTER        non-solid monster?
CONTENTS_DEADMONSTER    dead monster
CONTENTS_DETAIL         brush that is not passed to vis - not in final BSP ?
CONTENTS_TRANSLUCENT    see through
CONTENTS_LADDER         ladder

MASK_ALL          -stop on anything
MASK_SOLID        -walls/windows
MASK_PLAYERSOLID  -anything you'd expect a player to stop on
MASK_DEADSOLID    -same as above, can go through monsters
MASK_MONSTERSOLID -anything you'd expect a monster to stop on
MASK_WATER        -any liquid
MASK_OPAQUE       -walls and liquid except water (which is see-through)
MASK_SHOT         -walls, monsters and dead monsters
MASK_CURRENT      -flowing brush

Written by Davo (smithd6@cs.man.ac.uk)
(parts marked //kami0 supplied by Michael 'kami0' DiGiovanni (kaze@concentric.net))

If there are any corrections, bugs etc, please e-mail me.

Please also note that this has been the result of searching through the c files supplied by
iD, and I don't have reference to any official documents or anything, so don't assume I know 
what I'm talking about ;).