Contributing

This repository is a practical, historically framed reference. Contributions should make it more accurate, safer, and easier to use without implying that a historical method is a substitute for modern professional practice.

Before you write

• Keep a change focused. Prefer one guide or one connected set of links per pull request, and explain any assumptions that affect the advice.
• Check the repository roadmap and index in README.md before adding a guide. New guides belong under fundamentals/, materials/, technology/, or knowledge/ and must be added to the README index.
• Use scoped language. State the era, region, climate, available feedstock, skill level, and tool assumptions when they change the result. Distinguish documented historical practice from estimates, modern reconstructions, and the contributor's inference. Avoid universal claims such as "always" or "every society" unless the evidence supports them.

Evidence and citations

Quantitative claims and claims with meaningful health, safety, environmental, or engineering consequences need an authoritative citation. Prefer primary sources, peer-reviewed research, standards bodies, museums or universities with subject expertise, and public-health or government agencies. Put the source next to the claim it supports, using a descriptive Markdown link. A bibliography alone is not enough when readers cannot tell which source supports which fact.

For measurements, yields, temperatures, doses, exposure limits, disease rates, or historical dates:

• Preserve the source's uncertainty, range, and operating conditions.
• Do not turn a laboratory result or a single historical example into a general guarantee.
• Cross-check high-stakes figures against a second authoritative source when practical, and record disagreements rather than silently choosing one.
• Never invent precision. Label calculations and extrapolations as such.

Guide structure

Every guide in the four guide directories must include all of the following:

# Guide title

**Difficulty:** a realistic assessment.
**Prerequisites:** links or a clear statement that there are none.

## Why it matters

## Failure modes

## Era notes

The text after Why it matters may further qualify the heading. Keep headings stable when possible because other pages may link directly to their anchors.

Use metric units as the primary units throughout: metres, kilograms, litres, degrees Celsius, and their appropriate multiples. Historical or US customary units may follow in parentheses when they help the reader interpret a source. Give tolerances or ranges where a single value would be misleading, and state whether percentages are by mass, volume, or another basis.

Safety review

Review every procedure for hazards before submitting it. This is especially important for heat and pressure, fire, confined spaces, mining and excavation, water and sanitation, food preservation, medicine, toxic metals, reactive or caustic chemicals, distillation, and machinery.

• Name the specific hazard, its credible failure modes, and practical controls close to the relevant step. Generic warnings are not sufficient.
• Include ventilation, containment, protective equipment, safe storage and disposal, and stop conditions where applicable.
• Do not present an improvised historical process as medical advice or as a safe replacement for regulated modern equipment, materials, or care.
• Check both acute and cumulative exposure, hazards to bystanders, and waste or contamination that persists after the work is finished.
• Remove or tightly scope procedural detail when it creates disproportionate risk without adding legitimate educational value.

Images and illustrations

• Give every informative image concise, descriptive alt text that communicates the useful subject or relationship rather than repeating its filename.
• Label AI-generated or reconstructed visuals in the adjacent caption. Treat them as orientation, never as historical evidence, an identification key, a safety demonstration, an equipment drawing, or proof of a process endpoint.
• For third-party images, record the creator or institution, original source page, license or public-domain basis, and modifications. Search-result pages and unattributed reposts are not sources.
• Prefer a few useful stage views over decoration. Keep raw material, intermediate state, and finished form visually distinct, and do not depict unsafe handling as normal practice.
• Store project images below assets/images/ and add a nearby asset record with generation prompts or external attribution as applicable.

Documentation checks

Before submitting, review every changed link and run the repository checker from the repository root. It uses only PowerShell's built-in features:

powershell -NoProfile -ExecutionPolicy Bypass -File .\scripts\check-docs.ps1

PowerShell 7 users can run the same check with:

pwsh -NoProfile -File ./scripts/check-docs.ps1

The checker validates local Markdown targets and heading fragments, local image targets and alt text, the guide schema above, and README index coverage. A successful run exits with status zero and prints a concise summary; any reported problem must be fixed before the change is ready for review.