Overview
EN ISO 3098-5:1997 - "Technical product documentation - Lettering - Part 5: CAD lettering of the Latin alphabet, numerals and marks" defines the general requirements for CAD (CADD) lettering used in technical product documentation and engineering drawings. Published as part of the ISO 3098 series, this part focuses on machine‑generated lettering for the Latin alphabet, numerals and common marks, including conventions for numerically controlled lettering and draughting systems.
Key topics and technical requirements
- Lettering types: Defines two principal CAD lettering families - type CB and type CA, each available in vertical (V) and sloped (S) variants. CA may be proportionally reduced to approximate type A forms.
- Spacing arrangements: Specifies proportional (P) and tabular (T) spacing modes for character placement.
- Character box and grid: Every character is defined within a character box and positioned using an imaginary grid system. Tables (3–6) show the graphic character sets for upper- and lower-case letters, numerals and marks.
- Dimensions and line widths: Lettering dimensions and line widths are given (see Table 1) for different nominal lettering heights; these provide consistent x‑height, stem, diacritical areas and baseline spacing.
- Alignment rules: Defines single points of alignment for characters, lines and text areas (table 2 and figures). Numeric values in decimal form are aligned by the decimal sign.
- Designation and identification: Prescribes a naming convention for a graphic character set (example: Lettering ISO 3098 - CB PVL - 3,5).
- Normative references: Works in conjunction with ISO 3098-0:1997 (general requirements) and ISO/TR 10623:1991 (CADD vocabulary).
Applications
- Standardizes CAD fonts and text generation in engineering drawings, assembly and manufacturing documentation.
- Ensures legibility and consistent presentation across CADD systems, numerically controlled plotters and CAD output devices.
- Supports interoperability between CAD toolchains, printed drawings and archival technical documentation.
- Useful when producing dimensioned drawings, parts lists, schematics and any technical graphics requiring standardized lettering.
Who uses this standard
- CAD administrators, drafting managers and technical authors
- Mechanical/architectural/engineering designers and drafters
- CAD software developers and font/renderer implementers
- Quality and documentation teams responsible for compliance with technical drawing conventions
Related standards
- ISO 3098-0:1997 - Technical product documentation - Lettering - Part 0: General requirements
- ISO/TR 10623:1991 - Vocabulary for computer-aided design and draughting (CADD)
- Other parts of ISO 3098 (Parts 1–4) for character sets beyond Latin
Keywords: ISO 3098-5, EN ISO 3098-5, CAD lettering, technical product documentation, CADD, lettering standard, Latin alphabet, numerals, character box, drawing lettering.