To provide a more precise "solid report" on this specific version, could you clarify if this is related to , a proprietary corporate tool , or a specific scientific dataset ?

The "z" at the end often signifies a development build , a private patch , or a beta version that follows the stable 3.5.1 release. Similar Scientific/Technical References

The AMS/EPA Regulatory Model (AERMOD) uses specific versioning for its technical guides and formulation documents.