{$open file.txt rb}

open creates a file stream. The second argument may be r (read), w (create and write) or a (create or append), but can be suffixed with + (read and write), b (to enable full buffering) or u (to disable buffering).

If no access mode is specified, the default is r (line-buffered, read-only access).

{$sem 5}

sem creates a semaphore stream.

{$sh {ls -la}}

sh creates pipe streams, attached to the standard I/O pipes of a shell command.

{$signal $SIGTERM}

signal creates a signal stream.

{$timer 5.3}

timer creates a timer stream.

{$inet.client tcp 10.0.0.138 80}

inet.client creates a TCP or UDP client stream.

{$inet.server tcp 0.0.0.0 8000 5}

inet.server creates a TCP or UDP server stream.

{$un.client dgram /tmp/server}

un.client creates a Unix socket client stream.

{$un.server dgram /tmp/server 5}

un.server creates a Unix socket server stream.

{$un.pair stream}

un.pair creates a pair of connected Unix socket streams.