This document presents a description of the work carried out in Milestone 4 (M4) of the ALMASI Project, which consists of creating a curated registry of training resources on Diamond Open Access (OA) scholarly publishing. The registry, provided as a structured spreadsheet, brings together around 250 training resources—including guidelines, courses, manuals, videos, learning modules, and supporting materials—available in English, Spanish, French, and Portuguese. Its aim is to support capacity building and professionalisation across non-profit publishing ecosystems by offering a diverse, well-organised collection of openly accessible materials. This document outlines the methodological approach (Annex I) used to identify, select, analyse, and classify the resources, prioritising relevance, quality, and practical reuse. The work is aligned with existing frameworks, notably the Diamond Open Access Standard (DOAS) and insights from related projects such as DIAMAS. It also introduces a structured metadata scheme designed to improve the description and reuse of training practices (Annex II), serving as a foundation for future capacity-building activities within ALMASI. The registry is conceived as a living resource, open to updates throughout the duration of the project, reflecting both the evolving landscape of Diamond OA training materials and ongoing linguistic or geographical imbalances. This document describes Milestone 4 (M4) of the ALMASI Project, published as the ALMASI Consortium (2026). Registry of Training Resources and Classification Schema (Version 1). Zenodo. DOI: https://doi.org/10.5281/zenodo.18428884. By consolidating and structuring this broad set of resources, M4 contributes to a more equitable, sustainable, and internationally aligned scholarly communication system, while supporting subsequent work on the development of learning pathways and training practices.