Principal Attributes of Linear Dimensions

DRAW Reference Manual

Dimensions : Linear Dimensions : Principal Attributes of Linear Dimensions

The example illustrates the attributes of a linear Dimension that most affect its general appearance. (Default values are in brackets.)

Note that OSHT, PLCL and DOFF are given initial default values at Layer level when the Layer is created. These values are cascaded down to Dimension level when those elements are created subsequently. Following this initial setting, an attribute set to ‘default’ at Dimension Point level takes its value from the same attribute of its owning Dimension element (if appropriate).

The Projection Line Clearance (PLCL) is the distance between the dimension point and the projection line at the dimension point end. Negative clearances can be specified. Examples of setting this attribute are:


PLCL 5	- set PLCL to 5mm
PLCL @	- set using cursor
PLCL DEF	- (at Dimension Point level): set to owning Dimension PLCL value

PLCL can be set at Dimension or Dimension Point level. PLCL set at Dimension level (which becomes the ‘default’ PLCL) applies to all subsequently created Dimension Points. PLCL set at Dimension Point level can only be reset from the same Dimension Point, not from Dimension level. When setting PLCL with the cursor, the resulting (paper) coordinate that does not lie in the same axis direction as the projection line is ignored. These comments also apply to the OSHT attribute.

The Projection Line Overshoot (OSHT) is the distance by which the projection line ‘overshoots’ the end of the dimension line. Negative overshoots cannot be specified. Examples of setting this attribute are:


OSHT 5	- set OSHT to 5mm
OSHT @	- set using cursor
OSHT @	- set using cursor
OSHT TOP /CIRCLE1	- OSHT defined by a ‘constructed point’. Refer to Point and Line Construction for further information.
OSHT DEF	- at Dimension Point level): set to owning Dimension OSHT value

(Refer to Principal Attributes of Linear Dimensions for further comments relating to OSHT.)

Other attributes are:


Dimension Line Offset (DOFF)	- the distance by which the dimension line is offset (in the projection line direction) from the 2D position of the first dimension point.
Projection Line Direction (PLDI)	- the angle between the projection line and the dimension line.
Dimension Line Direction (DIR)	- the direction of the dimension line (an explicit compass direction, p-point or p-line direction). Default East.

DOFF has a related attribute DPOS - the Dimension Line Position. DPOS is a fixed 2D paper coordinate through which the dimension line passes. DOFF and DPOS are mutually exclusive: setting one unsets the other. If a dimensioned element is moved the dimension line also moves when DOFF is used; if DPOS is used the dimension line still passes through the same point.

A feature of these four attributes (DOFF, DPOS, PLDI, DIR) is that although they are attributes of the Linear Dimension they can also be set at Dimension Point Level without the need to navigate to the Dimension element.

DOFF and DPOS both control the position of the dimension line and so are mutually exclusive - setting one unsets the other. Examples of the relevant commands are:


DOFF 20	- set DOFF to 20mm
DPOS @	- set DPOS using cursor
DIM ABSOLUTE	- convert DOFF to DPOS
DIM OFFS	- convert DPOS to DOFF

When setting DPOS, the resulting (paper) coordinate that does not lie in the same axis direction as the required offset is ignored.

The projection line direction is set by commands, for example:


PLDI 75	- set PLDI to 75 degrees
PLDI N10W	- set PLDI to explicit compass direction
PLDI THR/OUGH @	- set PLDI with cursor
PLDI IDP @	- set PLDI to nominated p-point direction