## Virtual Device Driver Reference for OS/2

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### Hook Interrupt Service (VDHInstallIntHook)

The handler supplied to this service is a post-reflection handler. Post- reflection handlers are called after the INT instruction is reflected into the DOS session interrupt code. A DOS session breakpoint address is put into the interrupt vector table entry at INIT time, so control returns to the kernel at the end of the DOS session's interrupt code chain. The virtual device driver interrupt handler chain is then called. The ROM routine address (or whatever was initially in the interrupt vector table), which was replaced by the DOS session breakpoint, is returned to, if the virtual device driver handlers do not call VDHPopInt. See VDHPopInt.