# O/S interoperability commands and functions

Execute Windows programs and/or access files using the O/S interoperability commands
 and functions.

Functioning occurs at the Windows O/S level, which imposes its own rules and constraints,
 such as:

- The uopen command and ucreate command return a Windows file-handle. These are a limited resource and must be released explicitly.

- The variable returned by the uexecute command, and used by the uwaitfor command or the umessage command, is also a Windows file-handle. Changing the variable, and then feeding the result to the uwaitfor command or the umessage command could cause unpredictable results.

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Source: https://d3codex.com/pickbasic-flashbasic/os-interoperability-commands/ - part of the D3Codex reference.