+/*
+PROTOCOL_DARKPLACES3
+server updates entities according to some (unmentioned) scheme.
+
+a frame consists of all visible entities, some of which are up to date,
+often some are not up to date.
+
+these entities are stored in a range (firstentity/endentity) of structs in the
+entitydata[] buffer.
+
+to make a commit the server performs these steps:
+1. duplicate oldest frame in database (this is the baseline) as new frame, and
+ write frame numbers (oldest frame's number, new frame's number) and eye
+ location to network packet (eye location is obsolete and will be removed in
+ future revisions)
+2. write an entity change to packet and modify new frame accordingly
+ (this repeats until packet is sufficiently full or new frame is complete)
+3. write terminator (0xFFFF) to network packet
+ (FIXME: this terminator value conflicts with MAX_EDICTS 32768...)
+
+to read a commit the client performs these steps:
+1. reads frame numbers from packet and duplicates baseline frame as new frame,
+ also reads eye location but does nothing with it (obsolete).
+2. delete frames older than the baseline which was used
+3. read entity changes from packet until terminator (0xFFFF) is encountered,
+ each change is applied to entity frame.
+4. sends ack framenumber to server as part of input packet
+
+if server receives ack message in put packet it performs these steps:
+1. remove all older frames from database.
+*/
+
+/*
+PROTOCOL_DARKPLACES4
+a frame consists of some visible entities in a range (this is stored as start and end, note that end may be less than start if it wrapped).
+
+these entities are stored in a range (firstentity/endentity) of structs in the entitydata[] buffer.
+
+to make a commit the server performs these steps:
+1. build an entity_frame_t using appropriate functions, containing (some of) the visible entities, this is passed to the Write function to send it.
+
+This documention is unfinished!
+the Write function performs these steps:
+1. check if entity frame is larger than MAX_ENTITYFRAME or is larger than available space in database, if so the baseline is defaults, otherwise it is the current baseline of the database.
+2. write differences of an entity compared to selected baseline.
+3. add entity to entity update in database.
+4. if there are more entities to write and packet is not full, go back to step 2.
+5. write terminator (0xFFFF) as entity number.
+6. return.
+
+
+
+
+
+server updates entities in looping ranges, a frame consists of a range of visible entities (not always all visible entities),
+*/
+