Some common Emacs mode-lines I gathered in random source codes.
Which is usually of form:
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-*- mode: modename; var: value; … -*-
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Common mode-lines, sorted by popularity (decreasing):

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mode: Noweb; noweb-code-mode: caml-mode 
mode: perl; 
mode: lisp-data; 
mode: Noweb; noweb-code-mode: c-mode 
mode: C; c-basic-offset: 3; 
mode: texinfo; coding: utf-8 
mode: C; buffer-read-only: t 
mode: lisp-data 
mode: c++; c-basic-offset: 4 
mode: troff; coding: UTF-8 
mode: latex; TeX-master: "Vorbis_I_spec"; 
mode: shell-script 
mode: Noweb; noweb-code-mode: lua-mode 
mode: so-long 
mode: perl 
mode: c++; 
mode: xml 
mode: texinfo; coding: utf-8; 
mode: texinfo 
mode: python 
mode: outline; coding: utf-8 
mode: Lisp; fill-column: 75; comment-column: 50; 
mode: C; mode: fold 
mode: C; c-file-style: "k&r"; tab-width 4; indent-tabs-mode: t; 
mode: sh 
mode: plstore 
mode: Perl; buffer-read-only: t 
mode: org; 
mode: Noweb; noweb-code-mode: sml-mode 
mode: fundamental; coding: euc-jp 
mode: cperl 
mode: c 
mode: reftex-index-phrases 
mode: MODE 
mode: Lisp; eval: (auto-fill-mode 1); 
mode: Lisp;
mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 
mode: text; fill-column: 256;
mode: text; coding: utf-8; fill-column: 70 
mode: texinfo; 
mode: rst 
mode: reftex-index-phrases; TeX-master: \"%s\" 
mode: prolog; coding: utf-8; fill-column: 78 
mode: org; coding: utf-8 
mode: org 
mode: octave; coding: utf-8 
mode: modula-2; m2-indent:3 
mode: indented-text; coding: utf-8 
mode: emacs-lisp; lexical-binding:t; coding: utf-8-emacs; 
mode: emacs-lisp 
mode: compilation 
mode: comint; local-variable: file; 
mode: shell-script; sh-set-shell: zsh 
mode: shell-script; sh-set-shell: bash 
mode: shell-script; 
mode: ruby 
mode: Perl 
mode: outline; coding: utf-8; 
mode: Outline 
mode: objc 
mode: Noweb; noweb-code-mode: icon-mode 
mode: Noweb; noweb-code-mode: caml-mode; comment-column: 32 
mode: MODE; 
mode: cperl; tab-width: 8; indent-tabs-mode: nil; basic-offset: 2 
mode: cperl; coding: utf-8-unix; 
mode: C++; eval: (auto-fill-mode 1); 
mode: asm 
mode: troff; coding: utf-8 
mode: po; coding: utf-8; 
mode: perl; perl-indent-level: 2; 
mode: outline; 
mode: notexist; mode: text 
mode: gitignore; 
mode: Emacs-Lisp; coding: utf-8; 
mode: cperl; cperl-indent-level: 4 
mode: c; c-basic-offset: 4 
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