(a) it contains a list of all references (sources of information), presented in accordance with the layout style guideline;
(b) reliable sources are cited inline. All content that could reasonably be challenged, except for plot summaries and that which summarizes cited content elsewhere in the article, must be cited no later than the end of the paragraph (or line if the content is not in prose);[2]
@Iazyges: More to follow, but to get you started:
Images
Strictly, a portrait or image on a coin is not a "bust", which applies to sculpture.
Done
Prose and coverage.
"Extant artifacts of his coinage as augustus are extremely limited". This sounds contrived, and is arguably ungrammatical. "Extant" is then used a second time in the same sentence. Any chance of rephrasing it?
Done
Who is Curtis Clay?
Done
Under Numanistics you use "bust" again. See above.
Done
Why are Aureus and Half-Aureus capitalised?
Done
"Diadumenian was born on 14 September 208, named Marcus Opellius Diadumenianus, to Macrinus, the Praetorian Prefect and future emperor, and his possibly fictitious wife Nonia Celsa. Diadumenian was elevated to caesar in April 217, at Zeugma, while his guard was escorting him from Antioch to Mesopotamia, to join his father." To my mind there is a discontinuity between these two sentences. Consider inserting a sentence stating that Macrinus had become emperor.
Done
"He was also given the name Antoninus, in honor of the Antonine dynasty, at this time. Elagabalus revolted at Emesa on 16 May 218, after which Macrinus led his legions to the praetorian fort at Apamea." To my mind there is a discontinuity between these two sentences. Consider inserting a sentence stating who Elagabalus was, and, perhaps, why he revolted.
Done
Several links in the lead are repeated in the main text.
"After Macrinus was defeated by Elagabalus on 8 June 218, at the Battle of Antioch, Macrinus fled north to the Bosporus, and entrusted Diadumenian to loyal servants, instructing them to take him into the Parthian Empire, to the court of Artabanus V, to ensure his safety. Diadumenian was captured en route in Zeugma, and executed in late June" An overlong sentence. Gog the Mild (talk) 21:30, 17 May 2018 (UTC)[reply]
^ Compliance with other aspects of the Manual of Style, or the Manual of Style mainpage or subpages of the guides listed, is not required for good articles.
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