Multi-valued Dimensions

The preceding examples have dealt with single-valued dimensions; where more than two Dimension Points are involved, the Dimension is said to be multi-valued. Two classes of multi-valued Dimensions exist, namely chained and parallel. An example of a chained Dimension is shown in Figure 12:5 below.

Figure 12:5. Chained Linear Dimension

Such a dimension (which is still represented by a single LDIM element) is created by repeating the TO part of the FROM . . . TO command line, moving the cursor crosshairs to each Dimension Point in turn. The example shown in Figure 12:4 in Linear Dimensions and How to Create Them would have been created by a command sequence such as:

NEW LDIM

FR ID @ TO ID @ TO ID @

An additional ‘link’ can be inserted in or added to a chained Dimension (or a single-valued Dimension can be ‘converted’ to a chained Dimension) through use of the INSERT command. This is done simply by entering:

INSERT ID @

and using the cursor to nominate the link element. P-points, p-lines, dimension points or 3D points may also be used as links using:

INSE IDP @

INSE IDPL @

INSE IDPD @ or

INSE POS @

A Dimension Point may be constructed using Draft’s point construction facilities (see Point and Line Construction). For example:

INSE POS OF @

INSE POS OF ENDP OF @

Other constructions such as INTERSECTION and MIDPOINT can be used. The facility (which is only valid in a plan or elevation View) enables Dimension Points to be positioned on any line of the Design graphics. The constructed Dimension Point will have a 3D position (that means, it is a DPOI) but will not be associated with the identified Design element.

The effect of the INSERT command is to create a new Dimension Point of the appropriate type at the correct position in the owning LDIM’s member list. INSERT can be used at Dimension Point or LDIM level. Figure 12:6 below illustrates the use of the INSERT command.

Figure 12:6. Use of the INSERT Command

Dimensions will be drawn in the same order as the LDIM’s member list order. If the elements get out of the correct order then the display of the Dimension will become confused. This situation can be corrected by the SORT DIMENSIONPOINTS command (minimum abbreviation SORT DIM), which can be used at Dimension or Dimension Point level. The effect of the command is shown in Figure 12:7 below.

Figure 12:7. Use of the SORT DIM Command

An example of a parallel Dimension is shown in Figure 12:8 below.

Figure 12:8. Parallel (or Tail) Linear Dimension

A parallel Dimension can be produced simply by setting the LCHA attribute of an LDIM as appropriate: