What meditation practice exactly is asubha?

This is what I have in my notes so far, but I really want to find some concrete evidence, besides AN 10.60, that it ONLY means 31 body parts. Or might it include corpse contemplation as well? Assuming MN 119 represents EBT, then kayagatasati includes 31asb, among several other practices.
So kayagata is a broader class of meditation subjects, but what is 'asubha bhavana' meditation? Is it only 31asb? 

So the two big questions relevant: 

1. What is the EBT position on exactly what meditation practices are included under 'asubha'? Is it only 31 body parts? Or does it also include corpse contemplation?
2. What is the official Theravada position, before Vimt. and Vism.? (they classify asubha as corpse contemplation, and 31 body parts under kayagata). B. Bodhi's footnote for SN 8.4 suggests official Theravada position is 31 body parts + 5 stages of corpse, but he doesn't cite source for that conclusion.

The reason the question is important

In passages such as SN 8.4 and AN 9.1, when it says, develop asubha, what exact practice is that?

a-subha 🧟‍ = un-attractive

✅in EBT meditation, it refers to 31asb🧟‍ body parts contemplation. See AN 10.60, AN 6.29.
⚠️300+ years after EBT, in Vimt. and Vism., Theravada re-defines asubha meditation to refer to 10 stages of corpse decay, and they reclassify 31asb🧟‍ under kāya-gatā-sati 🏃‍. It's important to know this, because in EBT suttas, an instruction to "develop asubha" is frequently mentioned, but without detail (examples: SN 8.4, SN 54.9). 31asb is immediately accessible, corpse contemplation considerably more complex.
• What's the purpose of asubha meditation? To counter perversions of our inverted perception AN 4.49, SN 8.4.
• But be careful, this is an advanced practice. Best to first have foundation in breath meditation SN 54.9.
• SN 12.61 and SN 12.62 is the more general case of seeing 4 elements via dependent origination 12ps as not being worth clinging to.

 SN 8.4,
(ānanda replies)

♦ “saññāya vipariyesā,	(your) perceptions (are) inverted,
cittaṃ te pari-ḍayhati.	[so the] mind (of) yours completely-burns,
♦ nimittaṃ pari-vajjehi,	(the) sign (to) completely-avoid:
subhaṃ rāg-ūpasaṃhitaṃ.	beauty connected-with-lust
♦ “saṅkhāre parato passa,	Co-doings; alien (they should be) seen (as),
dukkhato mā ca attato.	pain-&-suffering, not the self.
♦ nibbāpehi mahā-rāgaṃ,	Nirvanify [extinguish] (the) massive-lust,
mā ḍayhittho punap-punaṃ.	don’t burn again-(and)-again.
♦ “a-subhāya cittaṃ bhāvehi,	Non-beautiful [perceptions] (the) mind develops,
ek’-aggaṃ su-samāhitaṃ.	Singular-preoccupation, well-(developed)-undistractible-lucidity.
♦ sati kāya-gatā ty-atthu,	remembrance (of) body-condition,
nibbidā-bahulo bha.	disenchantment-(in)-abundance ***.
♦ “a-nimittañca bhāvehi,	Sign-less [meditation] (you) develop,
mān-ānusaya-mujjaha.	conceit’s-tendency,-discard.
♦ tato mān-ābhisamayā,	thereupon (with) conceit-penetrated,
upasanto carissasī”ti.	(in) peace (you) abide.

commentary says:

Saṃyutta Nikāya, sagāthāvagga-aṭṭhakathā, 8. vaṅgīsasaṃyuttaṃ, 4. ānandasuttavaṇṇanā

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♦ 212. catutthe rāgoti āyasmā ānando mahāpuñño sambhāvito, taṃ rājarājamahāmattādayo nimantetvā antonivesane nisīdāpenti. sabbālaṅkārapaṭimaṇḍitāpi itthiyo theraṃ upasaṅkamitvā vanditvā tālavaṇṭena bījenti, upanisīditvā pañhaṃ pucchanti dhammaṃ suṇanti. tattha āyasmato vaṅgīsassa navapabbajitassa ārammaṇaṃ pariggahetuṃ asakkontassa itthirūpārammaṇe rāgo cittaṃ anuddhaṃseti. so saddhāpabbajitattā ujujātiko kulaputto “ayaṃ me rāgo vaḍḍhitvā diṭṭhadhammikasamparāyikaṃ atthaṃ nāseyyā”ti cintetvā anantaraṃ nisinnova therassa attānaṃ āvikaronto kāmarāgenātiādimāha.

♦ tattha nibbāpananti rāganibbānakāraṇaṃ. vipariyesāti vipallāsena. subhaṃ rāgūpasañhitanti rāgaṭṭhāniyaṃ iṭṭhārammaṇaṃ. parato passāti aniccato passa. mā ca attatoti attato mā passa. kāyagatā tyatthūti kāyagatā te atthu. animittañca bhāvehīti niccādīnaṃ nimittānaṃ ugghāṭitattā vipassanā animittā nāma, taṃ bhāvehīti vadati. mānābhisamayāti mānassa dassanābhisamayā ceva pahānābhisamayā ca. upasantoti rāgādisantatāya upasanto. catutthaṃ.

subcommentary says:

Saṃyutta Nikāya, Sagāthāvaggaṭīkā, 8. Vaṅgīsasaṃyuttaṃ, 4. Ānandasuttavaṇṇanā

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♦ 212.Rāgoti ettha āyasmato vaṅgīsassa rāgassa uppattiyā kāraṇaṃ vibhāvetuṃ ‘‘āyasmā ānando’ ’tiādi vuttaṃ. Tanti ānandattheraṃ. Ārammaṇaṃ pariggahetunti kāyavedanādibhedaṃ ārammaṇaṃ satigocaraṃ. Asubhadukkhādito, rūpādiekekameva vā chaḷārammaṇaṃ aniccadukkhādito pariggaṇhituṃ paricchijja jānituṃ. Itthirūpārammaṇeti itthisantāne rūpasabhāve ārammaṇe.

♦ Nibbāpananti nibbāpayati etenāti nibbāpanaṃ. Vipallāsenāti asubhe ‘‘subhan’ti vipallāsabhāvahetu. Rāgaṭṭhāniyanti rāguppattihetu. Iṭṭhārammaṇanti subhārammaṇaṃ. Ettha ca iṭṭhārammaṇasīsena tattha iṭṭhākāraggahaṇaṃ vadati. Tañhi vajjanīyaṃ. Paratoti avasavattanatthena aññato. Saṅkhārā hi ‘‘mā bhijjantū’ti icchitāpi bhijjanteva, tasmā te avasavattittā paro nāma, sā ca nesaṃ paratā aniccadassanena pākaṭā hotīti vuttaṃ ‘‘parato passāti aniccato passā’ ’ti. Kāmaṃ vipassanā saṅkhāranimittaṃ na pariccajati saṅkhāre ārabbha vattanato, yesaṃ pana nimittānaṃ aggahaṇena animittāti gahituṃ arahati, taṃ dassetuṃ ‘‘niccādīnaṃ nimittānan’ ’tiādi vuttaṃ. Salakkhaṇa-sāmaññalakkhaṇa-dassanavasena mānassa dassanābhisamayo, vipassanāya pahānābhisamayo. ‘‘Maggenā’ti vadanti, maggeneva pana asammohato pariññāpaṭivedhavasena dassanābhisamayo, pahānapaṭivedhavasena pahānābhisamayo. Rāgādisantatāyāti rāgādīnaṃ samucchedavasena paṭippassaddhivasena vūpasametabbato santabhāvena.

B. Bodhi footnotes to SN 8.4 says

* The meditation on foulness (asubha) is the contemplation of the parts of the body, as at SN 51.20 (V 278,6-14), 

* or the cemetery meditations, as at SN 46:57-61

Is B. Bodhi getting that information from the commentary or subcommentary?

SN 51.20 has: (part of 4ip iddhipada formula, not called 'asubha', but code phrase 'as below, so above')

yathā adho tathā uddhaṃ,

“kathañca, bhikkhave, bhikkhu	"what (is) {dwelling}, *********, *******
yathā adho tathā uddhaṃ,	as below, so above,
yathā uddhaṃ tathā adho	as above, so below
viharati?	{********}?
idha, bhikkhave, bhikkhu	here, monks, (a) monk [practices the following:]

STED (31asb) a-subha

STED (31asb) un-attractive [body parts]

imameva kāyaṃ	In-this-same body,
uddhaṃ pāda-talā	up (from the) feet-base,
adho kesa-matthakā	below head-hair-(on)-top,
Taca-pariyantaṃ	Skin-enclosed,
pūraṃ nāna-p-pakārassa A-sucino	Full-of many-*-things Im-pure.
paccavekkhati:	(he) reflects:
‘atthi imasmiṃ kāye	There-are in-this body:
kesā lomā nakhā dantā taco,	Head-hairs, body-hairs, nails, teeth, skin,
maṃsaṃ nhāru aṭṭhi aṭṭhi-miñjaṃ vakkaṃ,	flesh, tendons, bones, bone-marrow, kidneys,
hadayaṃ yakanaṃ kilomakaṃ pihakaṃ papphāsaṃ,	heart, liver, pleura, spleen, lungs,
antaṃ antaguṇaṃ udariyaṃ karīsaṃ,	Large-intestines, small-intestines, stomach, feces,
pittaṃ semhaṃ pubbo lohitaṃ sedo medo,	bile, phelgm, pus, blood, sweat, fat,
assu vasā kheḷo siṅghāṇikā lasikā muttan’ti.	tears, skin-oil, saliva, mucous, fluid-in-the-joints, (and) urine.
evaṃ kho, bhikkhave, bhikkhu	such indeed, {he dwells} **********, *******
yathā adho tathā uddhaṃ,	as below, so above,
yathā uddhaṃ tathā adho	as above, so below,
viharati.	{********}.

AN 9.1 commentary says:

(commenting on phrase 'asubha bhavetabba'). It seems to talk about eating and going somewhere to do practice, but I'm not sure if it ever explains what the asubhakammaṭṭhānena  (meditation topics for asubha) are.

Aṅguttara Nikāya, navakanipāta-aṭṭhakathā, 1. paṭhamapaṇṇāsakaṃ, 1. sambodhivaggo n, 1. sambodhisuttavaṇṇanā

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♦ 1. navakanipātassa paṭhame sambodhipakkhikānanti catumaggasaṅkhātassa sambodhissa pakkhe bhavānaṃ, upakārakānanti attho. pāḷiyaṃ āgate nava dhamme sandhāyevaṃ pucchati. kā upanisāti ko upanissayapaccayo. abhisallekhantīti abhisallekhikā. samathavipassanācittassa vivaraṇe sappāyā upakārakāti cetovivaraṇasappāyā. appicchataṃ ārabbha pavattā kathā appicchakathā. sesesupi eseva nayo.

♦ asubhā bhāvetabbā rāgassa pahānāyāti ayamattho sālilāyakopamāya vibhāvetabbo — eko hi puriso asitaṃ gahetvā koṭito paṭṭhāya sālikkhette sāliyo lāyati. athassa vatiṃ bhinditvā gāvo pavisiṃsu. so asitaṃ ṭhapetvā yaṭṭhiṃ ādāya teneva maggena gāvo nīharitvā vatiṃ pākatikaṃ katvā punapi asitaṃ ādāya sāliyo lāyi. ettha sālikkhettaṃ viya buddhasāsanaṃ daṭṭhabbaṃ, sālilāyako viya yogāvacaro, asitaṃ viya paññā, lāyanakālo viya vipassanāya kammakaraṇakālo, yaṭṭhi viya asubhakammaṭṭhānaṃ, vati viya saṃvaro, vatiṃ bhinditvā gāvīnaṃ pavisanaṃ viya sahasā appaṭisaṅkhāya pamādaṃ ārabbha rāgassa uppajjanaṃ, asitaṃ ṭhapetvā yaṭṭhiṃ ādāya paviṭṭhamaggeneva gāvo nīharitvā vatiṃ paṭipākatikaṃ katvā puna koṭito paṭṭhāya sālilāyanaṃ viya asubhakammaṭṭhānena rāgaṃ vikkhambhetvā puna vipassanāya kammaṃ ārabhanakālo. imamatthaṃ sandhāya vuttaṃ — “asubhā bhāvetabbā rāgassa pahānāyā”ti.

♦ tattha rāgassāti pañcakāmaguṇikarāgassa. mettāti mettākammaṭṭhānaṃ. byāpādassa pahānāyāti vuttanayeneva uppannassa kopassa pajahanatthāya. ānāpānassatīti soḷasavatthukā ānāpānassati. vitakkupacchedāyāti vuttanayeneva uppannānaṃ vitakkānaṃ upacchedanatthāya. asmimānasamugghātāyāti asmīti uppajjanakassa mānassa samugghātatthāya. anattasaññā saṇṭhātīti aniccalakkhaṇe diṭṭhe anattalakkhaṇaṃ diṭṭhameva hoti. etesu hi tīsu lakkhaṇesu ekasmiṃ diṭṭhe itaradvayaṃ diṭṭhameva hoti. tena vuttaṃ — “aniccasaññino, bhikkhave, anattasaññā saṇṭhātī”ti. diṭṭheva dhamme nibbānanti diṭṭheyeva dhamme apaccayaparinibbānañca pāpuṇātīti imasmiṃ sutte vaṭṭavivaṭṭaṃ kathitaṃ.