SQL syntax in the help of transact-SQL

The following rule is used for the syntax relationship diagram in the reference of transact-SQL.
Specification
Uppercase Transact-SQL keywords.
Parameters provided by users in the Italic Transact-SQL syntax.
| (Vertical bars) Separate the syntax items in parentheses or braces. Only one project can be selected.
[] (Square brackets) Optional syntax items. You do not need to enter square brackets.
{} (Braces) is a required syntax item. Do not enter braces.
[,... N] indicates that the previous item can be repeated n times. Each item is separated by a comma.
[... N] indicates that the previous item can be repeated n times. Each item is separated by a space.
Bold Database Name, table name, column name, index name, stored procedure, utility, data type name, and text that must be displayed as is.
<Tag >::= name of the syntax block. This rule is used to group and tag excessively long syntaxes or syntactic unit parts that can be used in multiple positions in a statement. The syntax block is suitable for each position represented by a label enclosed in angle brackets: <tag>.