Proprietary Graphical Formats vs. Text-Based XMI for Version Control

Direct Answer

No, the loss of layout precision in text-based models does not outweigh the merge conflict risks of proprietary graphical formats. For long-term model repeatability across toolsets, text-based XMI with a dedicated rendering engine is the superior approach.

Why XMI Wins for Version Control

Confirmed Behavior

• XMI is text-based XML, producing clean, line-oriented diffs that Git can merge automatically in most cases.
• Proprietary binary formats (e.g., Enterprise Architect .eapx, Visual Paradigm .vpp) store absolute coordinates for every element. A single diagram resize changes hundreds of lines, creating noise that obscures structural changes.
• Merge conflicts in binary formats require specialized tools or manual resolution; text-based conflicts are resolvable with standard Git tooling.

Layout Precision Is Usually Cosmetic

Architectural meaning lives in structure—classes, relationships, multiplicities, stereotypes—not in whether a class sits at (142, 308) vs. (145, 310). Modern rendering engines (PlantUML, Mermaid, yEd, GraphViz) recompute layout algorithmically from structure. The visual output remains consistent and readable without storing coordinates.

Long-Term Repeatability Across Toolsets

Recommended Stack

1. Authoritative format: XMI 2.5.1 (OMG standard) exported from your primary modeling tool.
2. Rendering: PlantUML or Mermaid for documentation; yEd or GraphViz for interactive layout.
3. Layout persistence (if required): Store a separate, human-readable layout hints file (e.g., YAML with node IDs and relative constraints) that rendering engines can consume optionally.

Validation Step

Before committing to a toolchain, run a round-trip test:

# Export from Tool A → XMI → Import into Tool B → Export → Diff
# Verify only structural elements differ, not layout coordinates

If structural elements (classes, associations, properties) survive unchanged, the workflow is repeatable.

When Proprietary Formats Might Be Justified

• Regulatory requirements mandate pixel-perfect diagram reproduction (rare).
• Team uses a single tool exclusively with no migration plans, and has invested in a binary-aware merge tool.

One Diagnostic Question

Does your organization have a hard requirement for pixel-identical diagram reproduction across renders, or is structural fidelity with readable auto-layout sufficient? This determines whether you need the separate layout-hints file.