List of constants in hlsdk_const.inc

pev(entity, pev_button) or pev(entity, pev_oldbuttons) values
pev(entity, pev_flags) values
engfunc(EngFunc_WalkMove, entity, Float:yaw, Float:dist, iMode) iMode values
pev(entity, pev_movetype) values
pev(entity, pev_solid) values

Note

Some movetypes will cause collisions independent of SOLID_NOT and
SOLID_TRIGGER when the entity moves. SOLID only effects OTHER entities
colliding with this one when they move - UGH!
pev(entity, pev_deadflag) values
new Float:takedamage, pev(entity, pev_takedamage, takedamage) values
pev(entity, pev_effects) values
Spectating camera mode constants

Note

These constants are linked to different camera modes available when you
are spectating (either dead or when in spectator team). Usually this is
stored in the pev_iuser1 field in Counter-Strike and Half-Life games.
engfunc(EngFunc_PointContents, Float:origin) return values
Instant damage values for use with the 3rd parameter of the "Damage" client message.
Valid constants for fNoMonsters parameter of EngFunc_TraceLine, EngFunc_TraceMonsterHull, EngFunc_TraceHull and EngFunc_TraceSphere.
The hullnumber paramater of EngFunc_TraceHull, EngFunc_TraceModel and DLLFunc_GetHullBounds
global_get(glb_trace_flags)
Used with get/set_es(es_handle, ES_eFlags, ...) (entity_state data structure)
pev(entity, pev_spawnflags) values
func_train
func_wall_toggle
func_converyor
func_button
func_rot_button
env_global
multisource
momentary_rot_button
button_target
func_door, func_water, func_door_rotating, momementary_door
gibshooter
env_funnel
env_bubbles
env_blood
env_shake
env_fade
env_beam, env_lightning
env_sprite
env_message
env_explosion
func_tank
grenade
item_suit
game_score
game_text
game_team_master
game_team_set
game_player_hurt
game_counter
game_player_equip
game_player_team
func_trackchange
func_tracktrain
trigger_push
trigger_hurt
trigger_auto
trigger_relay
multi_manager
env_render

Note

These are flags to indicate masking off various render parameters that
are usually copied to the targets
trigger_changelevel
trigger_endsection
trigger_camera
func_rotating
triggers
func_breakable
func_pushable (also func_breakable, so don't collide with those flags)
light_spawn
Monster Spawnflags
info_decal
worldspawn
Set this bit on guns and stuff that should never respawn
Valve Mod Weapon Constants
Cap bits to indicate what an object's capabilities are, currently used for save/restore and level transitions.