MIL-PRF-28000B
3.2.1.2 Information requirements and data functionality. Two-dimensional geometry and annotation entities
form the majority of data items although some non-geometric information is required as well. Information
requirements for this application subset include (but are not limited to):
a.
Two dimensional geometry in the form of lines, circular arcs, conic arcs, and spline curves.
b.
Non-geometric attributes of line weight and line font.
c.
Annotation entities.
d.
Data relationships, including the concept of subfigures.
3.2.1.3 Data accuracy requirements. All data transformations shall maintain an accuracy of at least 0.001 units
on all parametric and coordinate values and all measurable dimensions. The generating system shall document
the accuracy of the file in global section field 19.
3.2.1.4 Mapping of information content to IGES subset entities. Illustration geometry shall be mapped into
two-dimensional IGES geometry entities and annotation entities. The composite curve, subfigure definition, and
subfigure instance entities shall be used to organize the illustration information to preserve any required data
relationships. Line weight and line style information shall be represented by the appropriate global and DE
parameters. Several entity structures in this subset have been included to keep the file size to acceptable levels.
For instance, the use of subfigures greatly reduces file size where illustration details are repeated. Similarly, the
general note entity is a compact method of representing annotation entity as compared with the stroking of each
character using line and arc geometry. However, there are instances where a system lacks the sophistication of
subfigure entity constructs or it is desired to stroke the text for a special appearance not otherwise attainable.
Lines, splines, linear curves, arcs, and conic arcs shall not have a zero arc length (zero length curves).
3.2.1.5 User conventions and data organization. A minimum complexity drawing/view entity combination,
along with its drawing size property, shall be used to assure an illustration will be created on all receiving
systems. The drawing shall be constructed in the positive quadrant. The origin point shall be located at the
lower left corner of the illustration.
3.2.1.6 IGES entity subset specification. Table II lists the entities of this subset. Only IGES entities which are
enumerated in this table shall be used for representing technical publication illustration product definition data.
Other valid IGES entity types may be present in the file as described by 3.1.1. Additional requirements are
placed on the global section of a file, and certain field value restrictions are also placed on the range of
parameter values in both the Directory Entry (DE) and the PD sections of a valid IGES file.
TABLE II. IGES entity content for Class 1 (Technical Illustration Subset)
ENTITY
FORM
ENTITY NAME
DE
PD
NOTES
NOTES
0
Null
100
Circular Arc
3
17
102
Composite Curve
1
4
104
1
Conic Arc
3
17, 20
7
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business