# Block References Block references give a paragraph or other document block a stable address so it can be linked or embedded elsewhere while retaining a relationship to its source. Roam, Obsidian, Notion, and related tools popularized this capability in personal knowledge systems. Atomic Markdown works at finer clause and sentence granularity, declares the unit during composition, and can transform the standalone surface rather than reproducing the source block unchanged. Related: [[wiki/Transclusion|Transclusion]], [[wiki/Resource Addressing|Resource Addressing]], [[wiki/Document Graph|Document Graph]], [[wiki/Content Atomization|Content Atomization]].