The _vload function takes a handle and copies the associated block of virtual memory into DOS memory. The function returns a far pointer to the location at which the block of memory is loaded. You use this pointer to read or modify the contents of the block.
The _vload function keeps the contents of the block in DOS memory only temporarily. The next time you call any function of the virtual memory manager, a loaded block may be swapped out to auxiliary storage, making the pointer returned by _vload invalid. Accordingly, you should access the contents of a loaded block only until the next call to the virtual memory manager.