FileMaker Script XML Specification

Reverse-engineered specification of FileMaker's undocumented fmxmlsnippet clipboard format. Every step ID, element ordering rule, and silent failure mode, established through empirical round-trip testing against production FileMaker solutions.

Developed by Andrew Kear of Clockwork Creative Technology and shared openly with the FileMaker/Claris community.

Why this exists

FileMaker's Script Workspace accepts pasted scripts in a specific XML format. Claris has never published a specification for it. Get the XML wrong and FileMaker accepts it silently, dropping data without any error message.

This specification documents what the paste handler actually accepts: 220 step IDs, canonical XML skeletons for every step, the element ordering constraints that cause silent drops when violated, and the calculation slot binding rules that cause multi-slot steps to misbind.

What it catches

The specification documents several classes of silent failure that are invisible in the Script Workspace after paste:

Set Variable name drop. If the variable name element is emitted as a single-letter tag instead of the canonical four-letter Name form, FileMaker pastes the step with no variable name. No error. No warning. You find out when the script runs.

Calculation slot misbinding. Install OnTimer Script, Perform JavaScript in Web Viewer, and other steps with multiple calculation slots silently bind a calculation to the wrong internal slot when elements are in the wrong order. The script appears to work. The calculation runs in the wrong context.

Element ordering. Several steps require child elements in a specific order. The XML is valid either way. Only one order produces the correct paste result.

These are not edge cases. They are the default failure mode when any tool, human or AI, generates FileMaker script XML without knowing the paste handler rules.

Packaged as a Claude Skill

The specification is packaged as a Claude skill with progressive loading: the model reads core rules plus only the step categories each task needs. This keeps token usage proportional to task complexity.

Once installed, Claude uses the specification automatically when generating or reviewing FileMaker script XML. The structural rules are handled deterministically. The model handles the logic.

Tested with Claude. Model agnostic by design. The deterministic approach means any capable model with the specification in context should produce reliable output. Claude is the only model Clockwork has tested against; others have reported success.

Beyond Claude

The specification is packaged here as a Claude skill, but the format rules are model-agnostic. The reference files are plain markdown, readable by any LLM or human. If you're building tools that generate FileMaker script XML, the spec is yours to integrate.

What's in the box

SKILL.md                            — Claude skill definition + routing index
references/
  core.md                           — Paste rules, conventions, Set Variable,
                                      silent failures, appendices (§1-7, A, B, C)
  steps-control.md                  — §8.1 Control
  steps-navigation-editing.md       — §8.3-8.4
  steps-fields-records.md           — §8.5-8.7
  steps-windows-files.md            — §8.8-8.9
  steps-accounts-ai-misc.md         — §8.2, §8.10-8.14
  steps-pdf.md                      — §8.15 PDF Files (FM 26)
  steps-plugin.md                   — §9 Plugin steps (MBS)
  custom-functions.md               — §11 Custom Functions
  worked-example.md                 — §10 Worked example (optional)

Installation

1. Download the zip from the Releases page
2. Extract to get SKILL.md and the references/ folder
3. Upload to your Claude organisation's skills library, preserving the folder structure

Upgrading from v1.12: replace all files. No new files this release, all changes are within the existing file set.

Upgrading from v1.11: replace all files. The references/steps-pdf.md file is new; all other files are updated in place.

Upgrading from v1.10.x: remove the old single references/filemaker_xml_rules.md and replace with the current file set.

Usage

Once installed, Claude applies the specification automatically when you ask for FileMaker scripts or fmxmlsnippet XML. No special prompt needed.

Generate a script:

"Write a FileMaker script that loops through the found set and sets a flag field"

Review existing XML:

Paste your fmxmlsnippet and ask Claude to review it for paste handler errors

With schema context:

Attach your DDR and Claude will use real field, layout, and script names from your solution. You can also attach a DDR exported using Clockwork Inspector.

Pasting into FileMaker

The Script Workspace accepts fmxmlsnippet type="FMObjectList" via clipboard paste in FileMaker's internal clipboard format, not plain text. This skill has been tested with the MBS Plugin in FileMaker 2024 and 2025. Paste handlers in FileMaker Pro 2026 remain compatible.

The FileMaker XML suite

One of a set that reverse-engineers FileMaker's clipboard format family end to end — the private type codes FileMaker uses to carry schema and objects through the clipboard. The three generation specs cover all seven codes between them; two tools support the workflow.

Script XML Skill (XMSS, XMSC, XMFN) The full script step ID dictionary, plus the hidden paste-handler rules that decide whether your XML survives the trip into FileMaker.

Layout XML Skill (XML2) All 18 layout object types mapped, every flag decoded, element order confirmed against native output. Verified across 45+ layouts in 10 production files.

Field, Table & Value List Definitions (XMFD, XMTB, XMVL) — this repo Field, table and value list definition XML — auto-enter, validation, storage, calculation options, and the three value list source arms — verified down to the individual option level.

Analysis — read, audit and clean existing XML

XML Inspector (SaXML) Full-catalog dependency analysis of a Save as XML export, entirely in the browser. Finds unreferenced fields, silent-failure risks, broken references, and diffs two versions of a solution against each other.

XML Scrubber (SaXML + others) Strips API keys, passwords and internal hostnames out of FileMaker XML before you hand it to an AI tool.

Licence

CC BY 4.0 — free to use, share, and adapt with attribution.

Contributing

Found something that doesn't round-trip? A production export that contradicts the spec? Open an issue or PR.

Version history