| Integrated application resource: Draughting | ISO 10303-101:2021(E) © ISO |
The subject of the draughting_dimension_schema is the dimension-related information. Through use of this schema it is possible to identify a collection of annotation curves, symbols, and text as those which present information about a dimension value and its unit of measure. This includes those collections which graphically depict the extent and direction of measure. It is also possible to maintain relationships, such as a common datum or baseline, between dimension presentations.
This clause defines the information requirements to which implementations shall conform using the EXPRESS language as defined in ISO 10303-11. The following EXPRESS declaration begins the draughting_dimension_schema and identifies the necessary external references.Each implementation of an AP that uses this schema and that encodes entity names shall use the encoding specified in Annex A. Each reference to this schema in an open system shall use the identifier encoding specified in Annex B. This schema is illustrated in Annex D using the EXPRESS-G notation.
EXPRESS specification:
*)
SCHEMA draughting_dimension_schema;
REFERENCE FROM
draughting_element_schema
--
ISO 10303-101
(dimension_curve,
leader_curve,
projection_curve,
draughting_callout,
draughting_callout_relationship,
dimension_curve_directed_callout,
leader_directed_callout,
projection_directed_callout,
dimension_extent_usage);
(*
NOTE 1 The schemas referenced above are specified in the following parts:
draughting_element_schema ISO 10303-101
NOTE 2 See Annex D for a graphical representation of this schema.
The draughting presentation of dimensions and their related information is accomplished using specialized combinations of draughting elements, such as annotation curves, text, and symbols. The combinations of annotation curves, text, and symbols used for presenting dimension information, are the same combinations used elsewhere in draughting, except that the information being presented is that of a dimension.
The presentation of dimension information may be independent of or directed to the draughting presentation of the feature being dimensioned by such draughting elements as leader lines, projection lines, or dimension lines.
Dimension lines direct information about the dimension size or location and depict graphically the extent of the dimension and the direction of measurement.
A dimension graph is a combination of draughting elements that incorporate a dimension line, depicting the extent and direction of a dimension measurement.
Dimension graphs may be successively positioned in a sequence. If so, they may share projection lines.
The type of the dimension graph does not always match the nature of the dimension being presented. An angular dimension graph always presents an angular dimension, but a diameter dimension may be presented by a linear form of the dimension graph as well as by the diameter form of the dimension graph.
NOTE Figure 18 gives examples of two forms of the dimension graph; both graphically present the same diameter dimension.
Draughting Application Protocols may further specialize resources found in this schema or in ISO 10303-46 to obtain draughting concepts not explicitly provided.
When the information about a measurement is referred to a place on the drawing by means of a leader line or projection line, the dimension_callout shall also be a leader_directed_callout or a projection_directed_callout.
When the extent and direction of a measurement are represented by a dimension line or curve, the dimension_callout shall also be a dimension_curve_directed_callout.
When a dimension_callout, which is dimension curve directed, is to participate in chain or parallel dimension sequence, it shall also be a dimension_graph.
EXPRESS specification:
*)
ENTITY dimension_callout
SUBTYPE OF (draughting_callout);
WHERE
WR1: ('DRAUGHTING_ELEMENT_SCHEMA.LEADER_DIRECTED_CALLOUT'
IN (TYPEOF (SELF))) XOR
(SIZEOF (QUERY(dce_1 <* SELF\draughting_callout.contents |
('DRAUGHTING_ELEMENT_SCHEMA.LEADER_CURVE'
IN (TYPEOF(dce_1))))) = 0);
WR2: ('DRAUGHTING_ELEMENT_SCHEMA.PROJECTION_DIRECTED_CALLOUT'
IN (TYPEOF (SELF))) XOR
(SIZEOF (QUERY(dce_1 <* SELF\draughting_callout.contents |
('DRAUGHTING_ELEMENT_SCHEMA.PROJECTION_CURVE'
IN (TYPEOF(dce_1))))) = 0);
WR3: ('DRAUGHTING_ELEMENT_SCHEMA.DIMENSION_CURVE_DIRECTED_CALLOUT'
IN (TYPEOF (SELF))) XOR
(SIZEOF (QUERY(dce_1 <* SELF\draughting_callout.contents |
('DRAUGHTING_ELEMENT_SCHEMA.DIMENSION_CURVE'
IN (TYPEOF(dce_1))))) = 0);
END_ENTITY;
(*
Formal propositions:
WR1: A dimension_callout shall be a leader_directed_callout, else the dimension_callout shall contain no leader_curves.
WR2: A dimension_callout shall be a projection_directed_callout, else the dimension_callout shall contain no projection_curves.
WR3: A dimension_callout shall be a dimension_curve_directed_callout, else the dimension_callout shall contain no dimension_curves.
A dimension_graph may be positioned on the drawing in a chain or parallel sequence of one or more dimension_graphs. Such sequences of dimension_graphs shall be maintained by using the dimension_graph_sequence entity.
Projection lines, used to relate the dimension line or curve to a place or places on a drawing are shared between sequenced dimension_graphs. Where a dimension_graph either participates or may later participate in a chain or parallel sequence, projection lines shall be related to the dimension graph by using the dimension_graph_projection_curve_usage entity.
NOTE This provides a generalized dimension_graph. It may be necessary to use an Application Protocol to further specialize this entity to identify allowable forms such as angular, curve, diameter, linear, radius, etc.
EXPRESS specification:
*)
ENTITY dimension_graph
SUBTYPE OF (dimension_curve_directed_callout);
WHERE
WR1: SIZEOF(USEDIN(SELF,'DRAUGHTING_DIMENSION_SCHEMA.'+
'DIMENSION_GRAPH_PROJECTION_CURVE_USAGE.GRAPH')) <= 2;
WR2: SIZEOF(QUERY(dce <* SELF\draughting_callout.contents |
'DRAUGHTING_ELEMENT_SCHEMA.PROJECTION_CURVE'
IN (TYPEOF(dce)))) = 0;
WR3: 'DRAUGHTING_DIMENSION_SCHEMA.DIMENSION_CALLOUT'
IN (TYPEOF(SELF));
END_ENTITY;
(*
Formal propositions:
WR1: A dimension_graph shall only have projection lines provided by the dimension_graph_projection_curve_usage.
WR2: A dimension_graph shall be combined with at most two projection lines.
WR3: A dimension_graph is both a dimension_curve_directed_callout and a dimension_callout.
NOTE 1 A projection_curve may be used by more than one dimension_graph. When a projection_curve is shared, it may or may not play the same role with respect to both dimension_graphs.
EXPRESS specification:
*)
ENTITY dimension_graph_projection_curve_usage;
graph : dimension_graph;
projection_line : projection_curve;
role : dimension_extent_usage;
UNIQUE
UR1: graph, projection_line;
UR2: graph, role;
END_ENTITY;
(*
Attribute definitions:
graph: the dimension_graph that uses the projection_line.
projection_line: the projection_curve used by the dimension_graph.
role: the role of the projection_curve in the dimension_graph.
NOTE 2 The role of the projection_curve in the dimension_graph is either the origin or the target, corresponding to an extent of the dimension being depicted graphically. Where a dimension_graph_projection_curve_usage is to correspond with the dimension_curve_terminator, the same role should be assigned to both with respect to the extent of the dimension_graph.
Formal propositions:
UR1: The combination of graph and projection_line shall be unique within a population of dimension_graph_projection_curve_usages.
UR2: The role of the projection_line in the dimension_graph shall be unique.
NOTE ISO 129 [5] describes both parallel (baseline) and chain dimensioning. The relationship between dimension_graphs presenting information about two successive dimensions (either parallel or chain) can be maintained using specializations of this entity.
EXPRESS specification:
*)
ENTITY dimension_graph_sequence
SUBTYPE OF (draughting_callout_relationship);
WHERE
WR1: 'DRAUGHTING_DIMENSION_SCHEMA.DIMENSION_GRAPH' IN
TYPEOF (SELF\draughting_callout_relationship.
relating_draughting_callout);
WR2: 'DRAUGHTING_DIMENSION_SCHEMA.DIMENSION_GRAPH' IN
TYPEOF (SELF\draughting_callout_relationship.
related_draughting_callout);
END_ENTITY;
(*
Formal propositions:
WR1: The relating_draughting_callout (i.e., predecessor) shall be a dimension_graph.
WR2: The related_draughting_callout (i.e., successor) shall be a dimension_graph.
*)
END_SCHEMA; -- draughting_dimension_schema
(*
© ISO 2021 — All rights reserved