3. Conventions
The following conventions are used in the synopsis of a command: brackets ([ and]) indicate optional parts. (In the synopsis of a Tcl command, question marks (?) are used instead, as is usual in Tcl.) Braces ({ and}) and vertical lines (|) indicate that you must choose one alternative. Dots (...) mean that the preceding element can be repeated.
Where it enhances the clarity, SQL commands are preceded by the prompt=>, and shell commands are preceded by the prompt$. Normally, prompts are not shown, though.
Anadministrator is generally a person who is in charge of installing and running the server. Auser could be anyone who is using, or wants to use, any part of thePostgreSQL system. These terms should not be interpreted too narrowly; this book does not have fixed presumptions about system administration procedures.