DDC Thousands 400 - 499
400 Language CL
401 Philosophy & theory CL – TF5; CL – TT
402 Miscellany
403 Dictionaries & encyclopedias CL – T4b or T4a
404 Special topics Specify
405 Serial publications CL – T4h
406 Organizations & management PI4 (CL)
407 Education, research & related topics CL – PE
408 Kinds of persons treatment CL ^ I [very vague]
409 Geographic & persons treatment CL ^ N1
410 Linguistics TF7c
411 Writing systems GA6b – PI3
412 Etymology T7b – TF1
413 Dictionaries T4b
414 Phonology & phonetics TF7c (N8 > CL)
415 Grammar CL – PI3
416 [Unassigned]
417 Dialectology & historical linguistics CL – TF1
418 Standard usage & applied linguistics →iu TF7c
419 Sign languages CL (N8) [or hand language?]
420 English & Old English CL1en (Two-letter code from ISO639)
421 English writing system & phonology (GA6b – PI3)(CL1en); TF7c (N8 > CL1en)
422 English etymology (T7b – TF1) > CL1en
423 English dictionaries T4b (CL1en)
424 [Unassigned]
425 English grammar CL1en – PI3
426 [Unassigned]
427 English language variations CL4 (CL1en)
428 Standard English usage CL1en (QQ8)
429 Old English (Anglo-Saxon) CL1en (QT2) [or identify by time period]
430 Germanic languages; German CL1de (Two-letter code from ISO639)
431 German writing systems & phonology (GA6b – PI3)(CL1de); TF7c (N8 > CL1de)
432 German etymology (T7b – TF1) > CL1de
433 German dictionaries T4b (CL1de)
434 [Unassigned]
435 German grammar CL1de – PI3
436 [Unassigned]
437 German language variations CL4 (CL1de)
438 Standard German usage CL1de (QQ8)
439 Other Germanic languages CL1 [specify] [The synthetic approach does not privilege major languages, though we may need to move to three-letter codes for minor languages as ISO 639 has]
440 Romance languages; French CL1fr (Two-letter code from ISO639)
441 French writing systems & phonology (GA6b – PI3)(CL1fr); TF7c (N8 > CL1fr)
442 French etymology (T7b – TF1) > CL1fr
443 French dictionaries T4b (CL1fr)
444 [Unassigned]
445 French grammar CL1fr – PI3
446 [Unassigned]
447 French language variations CL4 (CL1fr)
448 Standard French usage CL1fr (QQ8)
449 Occitan & Catalan CL4 (CL1fr) (Cutter)
450 Italian, Romanian & related languages CL1it (Two-letter code from ISO639)
451 Italian writing systems & phonology (GA6b – PI3)(CL1it); TF7c (N8 > CL1it)
452 Italian etymology (T7b – TF1) > CL1it
453 Italian dictionaries T4b (CL1it)
454 [Unassigned]
455 Italian grammar CL1it – PI3
456 [Unassigned]
457 Italian language variations CL4 (CL1it)
458 Standard Italian usage CL1it (QQ8)
459 Romanian & related languages CL1ro (Two-letter code from ISO639)
460 Spanish & Portuguese languages CL1es; CL1pt (Two-letter code from ISO639)
461 Spanish writing systems & phonology (GA6b – PI3)(CL1es); TF7c (N8 > CL1es)
462 Spanish etymology (T7b – TF1) > CL1es
463 Spanish dictionaries T4b (CL1es)
464 [Unassigned]
465 Spanish grammar CL1es – PI3
466 [Unassigned]
467 Spanish language variations CL4 (CL1es)
468 Standard Spanish usage CL1es (QQ8)
469 Portuguese Cl1pt (Two-letter code from ISO639)
470 Italic languages; Latin CL1la
471 Classical Latin writing & phonology (GA6b – PI3)(CL1la); TF7c (N8 > CL1la)
472 Classical Latin etymology (T7b – TF1) > CL1la
473 Classical Latin dictionaries T4b (CL1la)
474 [Unassigned]
475 Classical Latin grammar CL1la – PI3
476 [Unassigned]
477 Old, postclassical & Vulgar Latin CL1la (QT2) or specify time period; CL1la (CE9)
478 Classical Latin usage →iu CL1la
479 Other Italic languages CL1 specify
480 Hellenic languages; classical Greek CL1el (QT2) [ISO 639 does not have a special code for classical Greek. We could introduce one.]
481 Classical Greek writing & phonology (GA6b – PI3)(CL1el (QT2)); TF7c (N8 > CL1el (QT2))
482 Classical Greek etymology (T7b – TF1) > CL1el (QT2)
483 Classical Greek dictionaries T4b (CL1el (QT2))
484 [Unassigned]
485 Classical Greek grammar CL1el (QT2) – PI3
486 [Unassigned]
487 Preclassical & postclassical Greek CL1el > N2 [specify time period]
488 Classical Greek usage →iu CL1el (QT2)
489 Other Hellenic languages CL1 specify
490 Other languages CL1 specify
491 East Indo-European & Celtic languages Specify individual languages; use >N1 or \CL1 to specify language groups by region or core language.
492 Afro-Asiatic languages; Semitic languages Specify individual languages; use >N1 or \CL1 to specify language groups by region or core language.
493 Non-Semitic Afro-Asiatic languages Specify individual languages; use >N1 or \CL1 to specify language groups by region or core language.
494 Altaic, Uralic, Hyperborean & Dravidian Specify individual languages; use >N1 or \CL1 to specify language groups by region or core language.
495 Languages of East & Southeast Asia Specify individual languages; use >N1 or \CL1 to specify language groups by region or core language.
496 African languages CL1 > N1b [Africa] Specify individual languages.
497 North American native languages S (QT6) – (CL1 > N1bn
498 South American native languages S (QT6) – (CL1 > N1b s
499 Austronesian & other languages Specify individual languages; use >N1 or /CL1 to specify language groups by region or core language.