DosQueryNPHState returns the following information about a pipe handle and the attributes of the pipe:

• The end of the pipe that the handle is for (server or client end)
  
• The pipe type (byte pipe or message pipe)
  
• The instance count
  
• The blocking mode (blocking or nonblocking)
  
• The read mode (byte-read mode or message-read mode).

The values for the pipe type and instance count cannot be changed, so they are always the same as those that were specified when the pipe was created with DosCreateNPipe. The information returned for blocking mode and read mode, however, can come from different sources:

• If the handle is for the server end of the pipe, then the blocking mode and the read mode were set with DosCreateNPipe, but may have been reset with DosSetNPHState.

• If the handle is for the client end of the pipe, then the blocking mode and the read mode were set to "blocking" and "byte-read" by the system when the client issued DosOpen. However, they may have been reset with DosSetNPHState.