SPEC: Motion and Program Syntax

3. Supported Syntax

3.1 Line structure

• optional block delete: /
• optional skip level: /0 through /9
• optional line number: N<integer>
• one motion command per line in GGroup1
• word letters are case-insensitive
• N block number must appear at block start
• block length overflow is rejected deterministically

3.2 Numbers

• integers: 0, 10, -3, +7
• decimals: 1.0, -2.5, .5, 5., +.25
• scientific notation is not supported in v0

3.3 G0 / G1

Supported words:

• G0
• G1
• Cartesian endpoints: X/Y/Z/A/B/C
• polar endpoints: AP=..., RP=...
• feed: F...

Rules:

• mixed Cartesian and polar endpoints in one line are rejected
• G0 is represented as a linear-motion family member with modal code G0
• RTLION and RTLIOF control rapid interpolation mode in the execution model
• current runtime-backed axis support is limited to X/Y/Z/A/B/C
• supported runtime-facing variable names in this slice:
  • simple $NAME
  • single-selector $NAME[part]
• deferred in this slice:
  • multi-selector forms like $P_UIFR[1,X,TR]
  • feed expressions
  • arc-word expressions

Examples:

G0 X20 Y10
G1 Z-2 F40
G1 X100 Y100 Z200
G1 AP=90 RP=10 F40
G1 G94 X100 Y20 Z30 A40 F100
G1 X=$P_ACT_X
G1 X=$AA_IM[X]

3.4 G2 / G3

Supported words:

• G2 clockwise arc
• G3 counterclockwise arc
• endpoints: X/Y/Z
• center words: I/J/K
• radius words: CR, AR
• polar endpoints: AP, RP
• intermediate-point form: CIP with I1/J1/K1
• tangential-circle form: CT

Plane behavior:

• AIL arc instructions carry plane_effective
• packet arc payloads carry plane_effective
• working-plane state constrains legal center words

3.5 G4

• G4 must be programmed in a separate NC block
• exactly one dwell value is required:
  • F... seconds
  • S... spindle revolutions
• prior feed and spindle state remain valid after dwell

3.8 Program naming and metadata

Current baseline:

• leading %... metadata line is accepted as external program metadata
• normalized name must remain non-empty and alphanumeric-led after normalization
• inline trailing comments are excluded from normalized metadata name
• the metadata line is preserved but not lowered as an executable block

Planned follow-up:

• stricter Siemens naming rules
• richer invalid-name diagnostics under compatibility modes

3.9 Subprogram syntax

Current baseline:

• direct call by bare or quoted name
• repeat count forms:
  • <name> P<count>
  • P=<count> <name>
• optional ISO call:
  • M98 P<id> when ISO mode is enabled
• returns:
  • RET
  • M17
• baseline declarations:
  • PROC <name>
  • PROC "<name>"

Execution/runtime baseline:

• subprogram_call resolves against labels
• repeat count loops the same target before resuming caller
• unresolved target or empty-stack return faults

3.10 M functions

Baseline syntax:

• M<value>
• M<address_extension>=<value>

Baseline rules:

• value range: 0..2147483647
• extended-address form requires =
• core flow M codes reject extended-address form
• known predefined Siemens M functions execute as accepted no-op control instructions in v0
• unknown M functions follow executor policy:
  • error
  • warning
  • ignore

3.11 Tool radius compensation

Supported words:

• G40
• G41
• G42

Current scope:

• parse
• AIL emission
• executor state tracking

Current limitation:

• no geometric cutter compensation is applied in v0

3.12 Working plane selection

Supported words:

• G17
• G18
• G19

Current scope:

• parse
• AIL emission
• executor state tracking
• arc-center validation against active plane

3.13 Tool selector syntax

Machine mode flag:

• tool_management

When tool_management=false:

• accepted:
  • T<number>
  • T=<number>
  • T<n>=<number>
• rejected:
  • non-numeric selector values
  • indexed form without =

When tool_management=true:

• accepted:
  • T=<location_or_name>
  • T<n>=<location_or_name>
• rejected:
  • legacy numeric shortcut without =

Runtime baseline:

• deferred mode stores pending tool selection until M6
• direct mode submits immediately
• M6 without pending selection falls back to active selection when present
• runtime tool acceptance follows the same Ready|Pending|Error contract as motion and dwell