{$open file.txt rb}
open creates a file stream. The second argument may be r (read), w (create and write) or a (create or append), but can be suffixed with + (read and write), b (to enable full buffering) or u (to disable buffering).
If no access mode is specified, the default is r (line-buffered, read-only access).
{$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.