Loads a language file for the construction of a language table. All of the language files that come with NSIS are in \W{../Contrib/Language files}{Contrib\\Language Files}
For ease of use LoadLanguageFile defines $\{LANG_language_file\} as the language id. Use it with \R{langstring}{LangString}, LangDLL and \R{viaddversionkey}{VIAddVersionKey}.
Defines a multilingual string. This means the its value will be different (or not, it's up to you) for every language. It allows you to easily make your installer multilingual without the need to add massive switches to the script.
Each LangString has a name that identifies it and a value for each language used by the installer. To use a LangString you must know its name. LangStrings can be used in any runtime string in the script. To use a LangString all you need to add to the string is $(LangString_name_here) where you want the LangString to be inserted.
Does the same as \R{langstring}{LangString} only it loads the string from a text/RTF file and defines a special LangString that can be used only by \R{alicensedata}{LicenseData}.
As of version 2 NSIS fully supports multiple languages. An installer can have more than one language. Each string in the installer can be easily translated using \R{langstring}{LangStrings}.
Each installer has one or more language tables which hold references to strings in the strings table. To create a language table all you need to do is use that language. Either use \R{loadlanguagefile}{LoadLanguageFile} or define a \R{langstring}{LangString} and you have built your installer a language table. To make sure all of the inner strings NSIS uses are there you should load a language file using use \R{loadlanguagefile}{LoadLanguageFile}. The strings from the language file will be used as defaults in case you don't define some strings in the script. The language file strings can be used by the script too, not just internally by NSIS. Each string in the language file is assigned to a specific LangString. That LangString's name is listed as a comment just above the string in the English language file for your convenience. The language file is located in \W{../Contrib/Language files}{Contrib\\Language Files}.
The LangDLL plug-in allows you to give the user an option to choose the language of the installer. Just push the language id ($\{LANG_*\}) and its name for every language in your installer, then the number of languages pushed, the caption, and the text that tells the user to select the language, call the plug-in function named LangDialog, pop the returned value into $LANGUAGE and you're good to go. If the user clicks on the cancel button the return value will be "cancel".
RTL languages are languages that are written from right to left. NSIS fully supports RTL languages. In the language file there is a place to specify if the language is RTL or not. If it is, NSIS will create another set of dialogs for the language that will be RTL. To find out on runtime if the language you're currently using is RTL or not check the value of the $(^RTL) language string. It will be 1 if the language is RTL and 0 otherwise.