Command
QisLib_GetDBU

QisLib_GetDBU

Function:
	int QisLib_GetDBU(double* Grid, double* Unit);

Inputs:
	Grid: Buffer to retrive grid value.
	Unit: Buffer to retrive units value.

Return:
	success: 0
	failure: one of the following values :

Errors:
	-1: The input argument in invalid. (null)
	-2: No GDSII or OASIS file has been opened.
	-3: File open in progress, operation not permitted.

Description:
	- This function can be used to get the database information (Grid and Units) stored in
	the header of the GDSII/OASIS file.
	- The 'Grid' represents user unit resolution. It can be interpreted as size of a
	database unit in user units.
	- The 'Unit' represents the length of a database tick in meters. It can be interpreted
	as the size of a database unit in meters.
	- Hence, if the Grid is 0.001 and Unit is 1e-09, it means that 1000 database units is
	equivalent to 1 user unit and the size of a user unit is 1e-06 (i.e 1e-09 / 0.001)
	meters or micron.
	- For OASIS files, 'Unit' must be ignored since the user units for OASIS files is
	always micron.

Example:
	GDSII Setup: Units @ Resolution 		QisLib_GetDBU returns:
	Grid, Unit
	micron @ 0.001 					0.001, 1e-9
	micron @ 0.25 					0.25, 2.5e-7
	mm @ 0.001 					0.001, 1e-6
	mil @ 0.1 					0.1, 2.54e-5