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+# Code Documentation for Lazarr!
+This file documents the code of this game.
+This file is still in WIP.
+
+## Function reference
+TODO
+
+## Node special fields reference
+This is a list of special fields for node definitions that Lazarr! recognizes:
+
+* `_lzr_active`: If the node has an 'active' counterpart, this contains the
+    itemstring of that 'active' counterpart.
+    Used by blocks that interact with laser
+* `_lzr_inactive`: If the node has an 'inactive' counterpart, this contains the
+    itemstring of that 'inactive' counterpart.
+    Used by blocks that interact with laser
+* `_lzr_on_toggle(pos, node)`: Function is called when a special
+    tool is used on this node.
+  `pos` is node position and `node` is node table
+* `_lzr_unlock(pos, node)`: Function is called on chests to unlock it.
+    `pos` is node position and `node` is node table
+* `_lzr_send_treasure(pos, node)`: Function is called on open chests
+    with treasure to start an animation that "sends" the treasure into
+    the sky. Used when a level is completed.
+    `pos` is node position and `node` is node table
+
+## Node groups reference
+This is a reference of all groups used for nodes.
+
+### Digging groups
+* `breakable=1`: Node is breakable with Ultra Pickaxe
+* `punchdig=1`: Node breaks when punched
+* `takable=1`: Node can be taken by player to be placed somewhere else
+
+### Gameplay groups
+* `rotatable`: Node is rotatable by hook item
+    * `1`: Always rotatable
+    * `2`: Rotatable if takable, or if in editor/menu
+    * `3`: Rotatable in editor/menu only
+* `laser_destroys`: Node is destroyed when a laser touches it
+    * `1`: Immediate destruction
+    * `2`: Node catches fire first, then is destroyed.
+           `_lzr_active` must contain the name of the burning variant.
+           The burning variant in turn must have `_lzr_inactive`
+* `flammable=1`: Node catches fire from neighboring burning blocks
+
+### Laser node groups
+* `laser=X`: Node is a laser (X=bitmask of active laser axes)
+  (not including blocks that *contain* a laser like an active mirror)
+* `laser_block=1`: Node interacts with laser
+
+#### Laser blocks
+Group rating 1 is for the inactive state, group rating 2 is for the active state.
+
+* `emitter`: Emitter
+* `detector`: Detector
+* `crystal`: Crystal
+* `mirror`: Mirror (normal)
+* `transmissive_mirror`: Transmissive Mirror
+* `crate`: Crate
+
+### Misc. categorization groups
+* `treasure=1`: Treasure
+* `teleporter`: Teleporter
+    * `1`: Off
+    * `2`: On
+* `chest`: Chest
+    * `1`: closed, unlocked
+    * `2`: closed, locked
+    * `3`: open, empty
+    * `4`: open, with treasure
+* `chest_closed=1`: Closed chest
+* `chest_open=1`: Open chest
+* `water=3`: Water
+* `liquid=3`: Node is a liquid in a semantic sense
+* `pane=1`: Pane (flat window-like block)
+* `stair=1`: Stair
+* `slab=1`: Slab
+
+## Item groups reference
+This is a reference of groups for all items that are not nodes.
+
+* `pickaxe=1`: Pickaxe
+* `bucket=1`: Bucket
+* `cheat_item=1`: Item is not supposed to be used in normal gameplay (e.g. for editor)