...except we have no clear mf2 standard yet for either one. discussion: https://chat.indieweb.org/dev/2019-08-08#t1565286782453800

https://indieweb.org/podcast shows two examples in the wild with length: aaronpk's is integer seconds, @gRegorLove's is PT1H7M59S. (what even is that?)

...and two examples with size, different human-readable versions: @aaronpk's 17.43mb, @gRegorLove's 62.2 MB.

RSS spec for length (integer bytes): http://www.rssboard.org/rss-specification#ltenclosuregtSubelementOfLtitemgt

iTunes details for duration (integer seconds): https://help.apple.com/itc/podcasts_connect/#/itc2b3780e76 , and example RSS: https://help.apple.com/itc/podcasts_connect/#/itcbaf351599

cc @jgmac1106