Based on:
ttcn-syntax:
    https://www.vim.org/scripts/script.php?script_id=753

    Folds: If the variable "g:ttcn_fold" is defined (e.g. by ":let g:ttcn_fold = 1" in your .vimrc file), folds will automatically be defined for each {...} block.

    Highlight: If the variable "g:ttcn_hl_naming_convention" (e.g. by ":let g:ttcn_hl_naming_convention = 1" in your .vimrc file), Language elements following generic naming conventions will be highlighted.
    This is not standardized but noted on https://www.ttcn-3.org/NamingConventions.htm.

ttcn-indent:
    https://www.vim.org/scripts/script.php?script_id=754

ttcn-ftplugin:
    https://www.vim.org/scripts/script.php?script_id=793
    You should put settings that are specific to TTCN in this file.

ttcn-dict:
    https://www.vim.org/scripts/script.php?script_id=767
    Keyword completion for TTCN-3.
    In insert mode you hit ctrl-x ctrl-k to get suggestions of keywords that could complete the currently typed word.
    Note: ctrl-x ctrl-k is the Vim built-in method for dictionary completion; check out vimtip #91 and vimtip #102 for cool stuff and adjustments you can make!

For information about TTCN-3, see https://www.etsi.org.