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+# Contributing to cdisc-org
+
+Thank you for contributing to CDISC's open source work. This guide explains how we estimate and track work across all repositories in the `cdisc-org` organization so that progress can be reported consistently to CDISC leadership and the broader community.
+
+---
+
+## Table of Contents
+
+1. [Work Estimation Overview](#work-estimation-overview)
+2. [T-Shirt Size Scale](#t-shirt-size-scale)
+3. [Submitting Issues](#submitting-issues)
+4. [GitHub Project Workflow](#github-project-workflow)
+5. [For Outside Collaborators](#for-outside-collaborators)
+6. [How This Feeds Leadership Reporting](#how-this-feeds-leadership-reporting)
+
+---
+
+## Work Estimation Overview
+
+We use **T-shirt sizing** to estimate the effort, complexity, and uncertainty of each issue. T-shirt sizes are a relative measure — not hours or days — which keeps estimates consistent across team members, time zones, and varying levels of technical background.
+
+The core principle: every issue is estimated *relative to other issues*, not in absolute time. A Medium issue is roughly twice as complex as a Small one. Over time, the distribution of sizes across a milestone gives leadership a reliable picture of scope and progress.
+
+This approach is used by the CDISC Data Science and COSA teams and is designed to be accessible to both internal contributors and outside collaborators.
+
+---
+
+## T-Shirt Size Scale
+
+| Size | Meaning | Rough Guidance | Example |
+|------|---------|----------------|---------|
+| **XS** | Trivial | A few hours | Update a config value, fix a typo in documentation |
+| **S** | Small | Half a day to a day | Add a field to an existing schema, update a README section |
+| **M** | Medium | A few days | Implement a small new feature with clear requirements |
+| **L** | Large | About a week | Refactor a module, new API endpoint, multi-repo coordination |
+| **XL** | Extra Large | Multi-week | Major architectural change or new integration — consider breaking down |
+
+> **Rule of thumb:** XL issues should be broken into smaller, independently deliverable issues before work begins whenever possible.
+
+---
+
+## Submitting Issues
+
+When opening a new issue in any `cdisc-org` repository:
+
+- **Set your own T-Shirt Size** — as the issue owner, you are responsible for selecting the size that best reflects the effort and complexity of your issue. Use the scale above as your guide.
+- **Write clear acceptance criteria** — the single biggest driver of estimation accuracy is understanding *what done looks like*. Use the format:
+  ```
+  Given [context], when [action], then [expected result].
+  ```
+- **Link related issues** — if your issue depends on or is blocked by another, note it in the description.
+- **Use the issue template** if one exists in the repository.
+
+If you are unsure of the right size, pick your best estimate and add a comment explaining your reasoning — a maintainer may adjust it if needed.
+
+---
+
+## GitHub Project Workflow
+
+All issues across `cdisc-org` repositories are tracked in the **CDISC IT & Open Source Org-Level Project**. Issues move through the following workflow:
+
+| Status | Meaning |
+|--------|---------|
+| **Backlog** | Issue is open but not yet estimated or scheduled |
+| **Ready** | Estimated and ready to be pulled into a sprint |
+| **In Progress** | Actively being worked on in the current sprint |
+| **In Review** | Pull request open, awaiting review |
+| **Done** | Merged and closed |
+
+**Custom fields on every issue:**
+
+- **T-Shirt Size** — XS / S / M / L / XL, set by the issue owner when the issue is created
+- **Iteration** — The sprint this issue is assigned to (2-week cycles)
+- **Milestone** — The release or roadmap milestone this issue contributes to
+
+---
+
+## For Outside Collaborators
+
+Welcome — we are glad to have you. Here is what you need to know:
+
+- **Open issues freely.** Set the T-Shirt Size field to your best estimate of the effort involved — use the scale in this guide.
+- **Pull requests are welcome** for issues labeled `good first issue` or `help wanted`.
+- **If you are picking up an unassigned issue**, leave a comment so the team can confirm it is ready and assign it to you.
+- **Milestone dates are set by the core team.** If you are working toward a milestone, check with the issue author or a maintainer to confirm the target date is still accurate.
+- **Questions?** Open a discussion in the relevant repository or reach out via the COSA community channels.
+
+All contributions, regardless of source, are tracked in the same GitHub Project so that reporting to CDISC leadership is unified.
+
+---
+
+## How This Feeds Leadership Reporting
+
+T-shirt sizes and iterations feed two key views used for leadership reporting:
+
+**Size distribution** — Shows the breakdown of XS / S / M / L / XL work remaining in a milestone. This gives leadership an at-a-glance read on scope: a milestone heavy in L and XL issues is a different conversation than one that is mostly S and M.
+
+**Milestone roadmap** — Each repository's milestones have target end dates. The org-level project roadmap view shows all active milestones across repos on a timeline, giving leadership a single view of what is in flight and when it is expected to land.
+
+These views are available in the GitHub Project's **Insights** tab and are refreshed automatically as issues are updated.
+
+---
+
+*This document is maintained by the CDISC Engineering team.