what examples of "well known functions" are there I can survey?

Some Sql Server documentation[ has these categories:

• Configuration Functions
  • Return information about the current configuration.
  • (N examples of "Configuration Functions", and more details here...)
• Conversion Functions
  • Support data type casting and converting.
  • (N examples of "Conversion Functions", and more details here...)
• Cursor Functions
  • Return information about cursors.
  • (N examples of "Cursor Functions", and more details here...)
• Date and Time Data Types and Functions
  • Perform operations on a date and time input values and return string, numeric, or date and time values.
  • (N examples of "Date and Time Data Types and Functions", and more details here...)
• JSON Functions
  • Validate, query, or change JSON data.
  • (N examples of "JSON Functions", and more details here...)
• Logical Functions
  • Perform logical operations.
  • (N examples of "Logical Functions", and more details here...)
• Mathematical Functions
  • Perform calculations based on input values provided as parameters to the functions, and return numeric values.
  • (N examples of "Mathematical Functions", and more details here...)
• Metadata Functions
  • Return information about the database and database objects.
  • (N examples of "Metadata Functions", and more details here...)
• Security Functions
  • Return information about users and roles.
  • (N examples of "Security Functions", and more details here...)
• String Functions
  • Perform operations on a string (char or varchar) input value and return a string or numeric value.
  • (N examples of "String Functions", and more details here...)
• System Functions
  • Perform operations and return information about values, objects, and settings in an instance of SQL Server.
  • (N examples of "System Functions", and more details here...)
• System Statistical Functions
  • Return statistical information about the system.
  • (N examples of "System Statistical Functions", and more details here...)
• Text and Image Functions
  • Perform operations on text or image input values or columns, and return information about the value.
  • (N examples of "Text and Image Functions", and more details here...)

Configuration Functions

• (list configuration-functions facts)

• @@DATEFIRST

• @@DBTS

• @@LANGID

• @@LANGUAGE

• @@LOCK_TIMEOUT

• @@MAX_CONNECTIONS

• @@MAX_PRECISION

• @@NESTLEVEL

• @@OPTIONS

• @@REMSERVER

• @@SERVERNAME

• @@SERVICENAME

• @@SPID

• @@TEXTSIZE

• @@VERSION

[@@DATEFIRST]

• how to [#datefirst-transact-sql]

[@@DBTS]

• how to [#dbts-transact-sql]

[@@LANGID]

• how to [#langid-transact-sql]

[@@LANGUAGE]

• how to [#language-transact-sql]

[@@LOCK_TIMEOUT]

• how to [#lock-timeout-transact-sql]

[@@MAX_CONNECTIONS]

• how to [#max-connections-transact-sql]

[@@MAX_PRECISION]

• how to [#max-precision-transact-sql]

[@@NESTLEVEL]

• how to [#nestlevel-transact-sql]

[@@OPTIONS]

• how to [#options-transact-sql]

[@@REMSERVER]

• how to [#remserver-transact-sql]

[@@SERVERNAME]

• how to [#servername-transact-sql]

[@@SERVICENAME]

• how to [#servicename-transact-sql]

[@@SPID]

• how to [#spid-transact-sql]

[@@TEXTSIZE]

• how to [#textsize-transact-sql]

[@@VERSION]

• how to [#version-transact-sql-configuration-functions]

Conversion Functions

• (list conversion-functions facts)

Cursor Functions

• (list cursor-functions facts)

Date and Time Data Types and Functions

• (list date-and-time-data-types-and-functions facts)

JSON Functions

• (list json-functions facts)

Logical Functions

• (list logical-functions facts)

Mathematical Functions

• (list mathematical-functions facts)

Metadata Functions

• (list metadata-functions facts)

Security Functions

• (list security-functions facts)

String Functions

• (list string-functions facts)

System Functions

• (list system-functions facts)

System Statistical Functions

• (list system-statistical-functions facts)

Text and Image Functions

• (list text-and-image-functions facts)