ISO 1302:2002's seven transcribed symbol-proportion rows (text height ->
line width d', short-leg height H1, minimum height H2) drive the 60 deg
vee, the machining-required bar at H1, the machining-prohibited circle
inscribed in the vee, and the all-around circle at the kink; the Ra/Rz
values, the process, the lay symbol and the machining allowance land
around the extension line, which grows with the widest of them. A text
height outside the seven rows is refused by name rather than
interpolated, and ISO 1302 is accepted as an alias designation for
drawings still issued under it - the graphical symbol is the same one.
ISO 2553:2019's reference line, dashed identification line (omitted for a
symmetrical weld, as the standard permits), size written before the
symbol, length and pitch written after it, field-weld flag, all-around
circle and process tail. Six elementary symbols are transcribed - square,
single-V, single-bevel, single-U, single-J, fillet. The rest of the
elementary table is deliberately not shipped: a weld kind outside the six
is refused with the list of the six, because a guessed weld symbol is a
wrong instruction to a welder.
Both tools place the symbol on a plain leader - a line plus an arrowhead
with the proportions the backend's own mleader already draws - rather
than through leader_create_mleader, which refuses empty text and would
hang an MTEXT label off every symbol.
Proportions neither standard dimensions (the all-around circles, the
flag, the identification line's dashes, the text pitch and the character
width estimate) are named constants documented as this implementation's
declared choices, never as transcribed values.
No new ActiveX member is called: both tools compose LINE / ARC / CIRCLE /
LWPOLYLINE / TEXT through the entity-creation contracts both engines
already implement, so no live COM probe was needed.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd
engineering/mech/ opens with the four modules every track-B/G branch imports,
so the four worktrees can be cut from this commit and none of them has to
invent a name the others will conflict with.
- primitives.py: the typed descriptions the pure modules emit (Line, Arc,
Circle, Poly, HatchArea, Text, DimIntent) with bbox / translate / rotate /
scale, and ROLE_LAYER - the one place an ISO 128 line role becomes a layer
name, so no module hardcodes a layer. The arc bbox sweeps its quadrants: a
0-180 arc reports y=+r, not its endpoints, which is what keeps the view
layout from stacking two views on top of each other.
- xdata.py: the ACADMCP_MECH codec in Track A's shape - a 1001 application
marker, 1000 chunks of at most 255 ASCII characters, the 16 KB per-entity
ceiling enforced before anything is written, and a foreign application, a
corrupt chunk stream, a wrong version or an unknown kind refused with
ValueError instead of decoded into something plausible.
- standards/__init__.py: the table registry. A size outside the coverage is
refused against the coverage; a size inside it that is not a listed row is
refused against the rows. Nothing is interpolated, an ambiguous variant is
never resolved by taking the first row, and a registration whose SOURCE does
not name the table it was transcribed from is refused.
- standards/materials.py: the section-hatch map for nine materials. ISO
128-50 standardises only the general hatching (narrow continuous lines at 45
degrees) - that is acadiso.pat ANSI31 and what engineering/gear.py already
draws for steel. The distinguishing symbols are ASME Y14.2M's section lining
as shipped in AutoCAD 2026's acadiso.pat, read off the installed file; cast
iron's departure from ASME and the absence of any mechanical symbol for
concrete and wood are stated in the rows themselves. Angles are 0.0 because
the patterns already carry 45 degrees, and the two architectural patterns'
scales are derived from the ANSI31 line spacing and recomputed by the test
rather than chosen.
No tool is registered here.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01FKFStjEFzpGyLq5bMpWxTd
