autocad-mcp-pro/.claude/skills/autocad-mcp-premium/references/iso-standards.md

ISO Standards Reference

Distilled tables for the standards this skill enforces.

ISO 128 — Line widths

Allowed lineweight set (mm), with 4:2:1 ratio rule:

Width	Common use
0.13	Hatch, dim text shadow
0.18	Hidden, center, phantom, dim text
0.25	Default text, leader
0.35	Auxiliary visible (where contrast needed)
0.50	Visible solid edges (most common production weight)
0.70	Heavy solid (large-scale parts), P&ID main process
1.00	Border, key heavy outlines
1.40	Title borders
2.00	Sheet outer border

Rule: every layer's lineweight must be one of these (or 0.0 = "Default" = inherits from active style). Anything else fails drawing_critique focus iso128.

ISO 128 — Line types

Type	Linetype name	Used for
Continuous thick	Continuous (0.50+ mm)	Visible edges
Dashed thin	HIDDEN (0.18–0.25)	Hidden edges
Chain thin	CENTER (0.18)	Centerlines, axes of symmetry
Chain double-dashed	PHANTOM (0.18)	Section / cutting plane / alternate position
Continuous thin	Continuous (0.18–0.25)	Dimensions, hatch, leaders

ISO 13567 — Layer naming (4-field)

Format: <Agent2c>-<Element6c>-<Presentation2c>-<Status1c>

Field	Length	Examples
Agent	2 chars	A=Architectural, S=Structural, M=Mechanical, P=Plumbing, E=Electrical
Element	6 chars	GEOMET=geometry, HIDDEN=hidden edges, DIMEN=dimensions, TITLE=title block
Presentation	2 chars	E=edge, T=text, H=hatch
Status	1 char	N=new, E=existing, D=demolish

Example layer set ships in engineering/layers.py::ISO13567_LAYERS.

ISO 129-1 — Dimensioning rules

1. Each dimension is given once — never repeat.
2. Extension lines project at least 8× line width past the dim line.
3. Decimal separator is the comma (per ISO; we accept point too).
4. Text orientation: read from below the drawing or from the right side.
5. Font: ISO 3098 (isocp.shx ships with AutoCAD).
6. Dimension styles: chain, baseline, ordinate are the three standard layouts — choose one per drawing and stick to it (dim_style in PlanSpec).

ISO 7200 — Title-block fields

Mandatory:

• Legal owner (Anka-Makine)
• Drawing number
• Title
• Date
• Sheet / total sheets
• Approver name + signature
• Creator name
• Document type

Common optional:

• Revision
• Scale (matches PlanSpec.scale)
• Projection symbol (1st angle ISO E vs 3rd angle ISO A)

This skill assumes you call titleblock_apply_iso_a3 (or its A3 cousin) to populate these fields after drawing_finalize's validator runs.

ISO 14617 / 10628 — P&ID symbology

When layer_set_id="pid" is passed to drawing_plan, the bootstrap creates the P&ID layer set:

Layer	Linetype	Lineweight	Purpose
PROCESS-PIPING-MAIN	Continuous	0.70	Main process line (heavy)
PROCESS-PIPING-SECONDARY	Continuous	0.50	Secondary process line
PROCESS-EQUIPMENT	Continuous	0.50	Vessels / pumps / drums
PROCESS-VALVES	Continuous	0.35	Valves & fittings
INSTRUMENT-SYMBOL	Continuous	0.35	Instrument bubbles (FCFs)
INSTRUMENT-LINE-SIGNAL	DASHED	0.18	Pneumatic / electrical signal
INSTRUMENT-TAG-TEXT	Continuous	0.25	Tag labels
ELECTRICAL-LINE	DASHDOT	0.18	Electrical line
UTILITY-LINE	PHANTOM	0.25	Steam / water / air utility
INSULATION-HATCH	Continuous	0.13	Insulation hatching

ISA-5.1 tag conventions (P&ID instruments)

<First letter><Second letter>-<Loop number><Suffix?>

First letter (measured variable)	Second letter (function)
F = Flow	T = Transmitter
P = Pressure	I = Indicator
T = Temperature	C = Controller
L = Level	V = Valve
A = Analytical	S = Switch

Examples: FT-101 (flow transmitter, loop 101), PCV-203A (pressure control valve, loop 203, A spare).