[postgis-devel] LWGEOM - XY,XYM,XYZ,XYZM

[strk at refractions.net]

The adt work is on its way. We now have an LWGEOM abstract data type
with deserialize/serialize/clone/release functionalities.

The GEOS<->POSTGIS conversion has been fixed to keep geometry structure,
and the summary() function has a new format for better debugging.

Before going on with constructurs I think it's important to decide
what to do with hasM, hasZ flags.

My idea was to use two flags so to support:
	XY 	- hasM=false hasZ=false
	XYM	- hasM=true hasZ=false
	XYZ	- hasM=false hasZ=true
	XYZM	- hasM=true hasZ=true

This would allow for space saving in the db and better semantic
specification.

In order to keep semantic in input/output WKT functions we might 
add a <GEOM>M type as a custom extension:

	POINT(1 2) 	<--> POINT
	POINT(1 2 3)	<--> POINTZ
	POINT(1 2 3 4)	<--> POINTZM
	POINTM(1 2 4)	<--> POINTM

Comments ?

--strk;