What it asks for
The standard requires the organisation to write down its own context (activities, interested parties, legal framework), to establish worker participation, to determine risks and opportunities, to set measurable objectives, to operate its processes, to measure performance and to review it at management level. It leaves the "how" to the organisation, which is why the same standard fits both a construction site and a software company.
Running them as one system
The safety, environmental and quality standards share the same high-level structure: context, leadership, planning, support, operation, performance evaluation, improvement. What is common is those top clauses; the sub-clauses and technical requirements differ. Shared documents, shared internal audits and a shared review are therefore possible — but "one procedure closed all three standards" is not.
In Optifora the management system module links clauses to records (risk, training, audit, incident), so an auditor can read from a list which record answers which clause.