Snippet.txt

:Snippet:
Usage: Type a few character → press Tab → a template of text is inserted
Stored in *.sublime-snippet located under any package’s folder
Appear under Tools | Snippets | <Your Package>.
Tools > New Snippet... → Sublime Text will present a snippet skeleton
Each *.sublime-snippet can only contain 1 snippet. To host multiple ones, use [[AutoComplete.txt#.sublime-completions]]
Use keybinding, We can
    load specific snippet, i.e: { "keys": ["%"], "command": "insert_snippet", "args": {"name": "Packages/XML/long-tag.sublime-snippet"} }
    insert snippet without creating a .sublime-snippet file, i.e: { "keys": ["%"], "command": "insert_snippet", "args": {"contents": "%$0%"} }
Example of .sublime-snippet:
    <snippet>
        <content>=dword:00000001</content>              //template of text to be inserted
        <tabTrigger>=d</tabTrigger>                     //Optional: Press this sequence of keys then Tab to insert snippet
        <scope>source.reg</scope>                       //Optional: limit the use of snippet to certain scope [[Scope.txt]]
        <description>dword in .reg file</description>   //Optional: Description to display in Snippets menu
    </snippet>
content:
    Example:    assert ${1:condition}, ${2:message}, ${3:continue=0}
    Must not contain ]]>  → Work around: insert an undefined/empty variable i.e: ]]$NOT_DEFINED>
    $ must be escaped with \$
    Always use tabs for indentation → on execute, tab is transformed to spaces if "translateTabsToSpaces": true
    Field markers $1  $2  $3 ... $n
        Tab/Shift+Tab will cycle cursor position through each field
        If field is repeated:
            First Name:$1, Last Name:$2, Full Name:$1 $2
            Multiple cursors appear at both positions → edit multiple fields at the same time
        $0   Specify exit point (cursor position after pressing Tab at the last fiels)
    Placeholders:
        Define default values i.e:  First Name: ${1:Guillermo}, Second Name: ${2:López}
        Can nest placeholders i.e:  Test: ${1:Parent ${2:Nested}}
    Can use variable
        Environment variables i.e: $TM_FULLNAME, $TM_FILENAME, $TM_TAB_SIZE, $TM_SOFT_TABS
        Custom variables defined in .sublime-options
        Example:  User name: ${1:$TM_FULLNAME}, Tab equal $TM_TAB_SIZE spaces
        Full list of variables:
            | $PARAM1 .. $PARAMn | Arguments passed to the insertSnippet command.                        |
            | $SELECTION         | The text that was selected when the snippet was triggered.            |
            | $TM_CURRENT_LINE   | Content of the line the cursor was in when the snippet was triggered. |
            | $TM_CURRENT_WORD   | Current word under the cursor when the snippet was triggered.         |
            | $TM_FILENAME       | Filename of the file being edited including extension.                |
            | $TM_FILEPATH       | Path to the file being edited.                                        |
            | $TM_FULLNAME       | User’s user name.                                                     |
            | $TM_LINE_INDEX     | Column where the snippet is being inserted, 0 based.                  |
            | $TM_LINE_NUMBER    | Row where the snippet is being inserted, 1 based.                     |
            | $TM_SELECTED_TEXT  | An alias for $SELECTION.                                              |
            | $TM_SOFT_TABS      | YES if translateTabsToSpaces is true, otherwise NO.                   |
            | $TM_TAB_SIZE       | Spaces per-tab (controlled by the tabSize option).                    |

Advanced example:
    %${0:$SELECTION}%        //wrap current selection in a pair of %