SuttaCentral
I am 80% (correction: 60%) sure that T 121 is actually (in part, possibly) a Mahāyāna sūtra. From the sūtra, with the usually tentative translation effort:
一切諸佛極方便求如來之藏生不可得，不生是佛性，於一切眾生所，無量相好清淨莊嚴。
“All of the myriad Buddhāḥ employ/study upāyakauśalya to seek the Tathāgata’s hidden arising (???) without being able to attain it, there is no arising of this Buddha nature (佛性) in all sentient beings (一切眾生), without limit thoughts beautiful and peaceful adorn it.”
Does anyone know more about T 121?
Could you please link to the sutta on SC?
Interesting. It is listed as a parallel to SN16.3
Not sure how I missed that…
That being said, the āgama is noticeably longer than the sutta. It might be a composite work, with many layers, some possibly Mahāyāna. I know literally nothing about it, so anythings possible!
Yes, I don’t know any Chinese but wouldn’t be surprised if some of the things found in the Chinese agamas (maybe later translations) had been expanded a “the edges”.
Well, this one is particularly suspect, perhaps, because it doesn’t seem to belong to any given “set” of āgamāḥ? They aren’t SA, MA, DA, etc.
This one was apparently “collected” with (an?) SA, but what that means I am not totally sure.
The independent Taishō sūtrāṇi uploaded here are an endless source of mystery to me! Where did they come from? How were they found/chosen?
Is it possible that the two are not parallels at all? I just screened the google translation of T 121 - it’s hilarious! With gems like
Tune the vicious evil digging magic…
What is the wickedness of the dolphin? Should study the Buddha…
Famous surname wins are satisfied with the foot, Sri Lanka by the smell of all the public know how to keep alive…
Haha, great Dada-dhamma 
But seriously, are SN 16.3 and T121 parallels?
Google Translate does an amazing job of the kind of Chinese used in these scriptures, he said with a certain amount of levity.
It regularly translates “Thus I have heard” as “If I smell”! 
Yes, it’s pretty obscure to me as well. there might be some information in the old catalogues.
The organization of the Taisho is based on the work of the Taisho editors, and doesn’t, so far as I know, closely resemble and traditional organization. Clearly this text is a composite of some kind. It’s quite possible that it isn’t really a “text” at all, but merely a few texts or passages that ended up together by chance.
This in fact seems likely, as near the end of the sutra there is a statement that the “Angulimala Sutra” is ended, and a subsequent textual remark that the “Simile of the Moon Sutra” is beginning. Then the text goes on with 如是我聞.
So it seems to have (at least) two unrelated portions, a sutra on Angulimala and one on the simile of the moon. Clearly it’s the latter that is parallel to SN 16.3, and this should be specified in our data. @vimala, can you add this additional specification:
["sn16.3", "sa-2.111", "sa1136", "t121#t0544b12-t0545a16", "~sf74"]
Note that the story of Angulimala was a popular one, and it’s possible but not certain that the text is, or contains, a parallel with the Pali sutta on Angulimala. In any case, as you have noted, it seems to contain Mahayana elements.
Done that in the newdata branch that is on staging but not sure if that is the right place to upload things now with the changes that are taking place.
Thanks. I think newdata should still be fine, but I will check this tomorrow.
T 15 may reference Mahāvairocana Buddha as 如來大日 (lit. “Tathāgata Great Sun”).
於天上人間， 無有能等者， 無畏大丈夫， 善斷貪愛病。
如來大日尊， 汝今稽首禮。
@ the gāthā after 249b25.
To Whom It May Concern:
I was doing some unrelated research on SC and came across this.
I know this topic is cold, but you might want to look into it again because T 121 is definitely not this Aṅgulimālīya Sūtra .
The real T 121 is a completely unrelated sutra which starts waaay down at the bottom of SC’s T121 page. T 121 is translated by Dānapāla (施護) while the Aṅgulimālīya Sūtra is translated by Guṇabhadra (求那跋陀羅). The Aṅgulimālīya Sūtra is actually T 120 (CBETA lists it as such). It’s translated in 4 fasicles and, in fact, the first fascile (卷第一) is SC’s T120, but somehow the final three (卷第二、卷第三、卷第四) got lumped in under T 121.
@Coemgenu Yes, indeed, it is a Mahāyāna sūtra–a tathāgatagarbha sūtra, to be precise. Here is a Wikipedia page on the sūtra:
https://en.wikipedia.org/wiki/A%E1%B9%85gulim%C4%81l%C4%ABya_S%C5%ABtra
(The Wikipedia page also has two links to English translations, if anyone’s interested.)
I forgot that I had read an article on this years ago where the author was comparing this version with the Pāli Aṅgulimāla Sutta to illustrate the process of how sāvakayāna suttas were “Mahāyānized” (which is actually what I was looking for because Dānapāla does the same thing sometimes: e.g., T 52).
I didn’t have time to check all the discourses listed, and I don’t know SC policy on these issues, but I would say it still counts as a (partial) parallel, at least to the Aṅgulimāla Suttas. The second sūtra, T 121, the one I was looking, as for what it parallels, I don’t know yet. But SC has two batches of parallels listed which, at first glance, seem to correspond to T 120 and 121.
Anyway, I’m glad I found the sūtra: I read the article but never the original text. And this thing looks crazy! I’m going to give it a look.
T121 looks like a legitimate Agama sutra that does parallel SN 16.3. T120 is a different story. It’s a Mahayana sutra inspired by the character of Angulimala. I think Rulu translated it: Yes, it’s here. The Taisho editors were a little loose with how they categorized texts. They put EBT texts like XT’s Itivrttaka translation in the back under “miscellaneous,” too.
So … what’s the upshot? Should T 120 be on SC or not?
If we compare to lives of the Buddha, something like Mahavastu does belong on SC, since even as a later text it has significant direct Sutta passages; whereas something like Buddhacarita does not belong on SC, since even when it gives stories or teachings found in the EBTs, it does so by retelling, not by quoting.
So a mere retelling of Angulimala’s story should not be on SC, but if it, eg., quotes the main verse of the story it should be.
Bhante–
May I suggest you consult the English translation at the link provided by Charles?
However, I can tell you that it is pretty far from the Pāli; and, according to the criteria you have given, I am thinking you probably wouldn’t want to keep it.
It isn’t just a mere retelling. It’s a creative new story about how Angulimala ended up killing a thousand people. It’s a Tathagata-garbha text using him as an example of a icchantika who still has the ability to be saved. It’s akin to the traditional Angulimala story the way the Mahayana Nirvana Sutra is akin to the Parinibbana Sutta, or the Avatamsaka Sutra is akin to the account of the Buddha after his enlightenment. The traditional story is just alluded to by a creative writer.
Edit: I just realized Rulu only translated the first fascicle. The passage that @coemgenu was noting in the OP is actually in the second fascicle. 如來之藏 is a translation of Tathagata-garbha. 藏 usually means something hidden, especially a place where valuable things are hidden. So, it can been a treasury. It was used to translate garbha as a result.
Sorry, I haven’t been following this thread closely enough. Checking back to the original CBETA source, it seems that the real probelms is that I mistakenly included the text of T 120 in T 121 when readying Chinese texts for SC.
The listed parallel is for t0544b12–t0545a16, which is in fact the scope of T121. And this is not a parallel for Angulimala, but for the Candupama Sutta, which appears to be correct.
So the appropriate action is to delete the text of T120 that was mistakenly added to T 121. I’ll do that, and thank you to all who helped figure this out.
Actually, he has all four fascicles: at the top of the page there are links to the other three (again, for anyone who might possibly be interested).