what's the difference between type a, b, and c?

//http://f-radiko.smartstream.ne.jp/*/_definst_/simul-stream.stream/playlist.m3u8?station_id=*&l=15&lsid=AAM_UUID&type=b (see connectionType b->areafree c->notfree?)

from the rajiko source code
it is a mystery

#EXT-X-PROGRAM-DATE-TIME:2023-10-24T01:00:00+09:00
#EXTINF:5,
https://media.radiko.jp/sound/b/LFR/20231024/20231024_010000_cibkp.aac
#EXT-X-PROGRAM-DATE-TIME:2023-10-24T01:00:05+09:00
#EXTINF:5,
https://media.radiko.jp/sound/b/LFR/20231024/20231024_010005_nkQlb.aac
#EXT-X-PROGRAM-DATE-TIME:2023-10-24T01:00:10+09:00
#EXTINF:5,
https://media.radiko.jp/sound/b/LFR/20231024/20231024_010010_HkpN3.aac
#EXT-X-PROGRAM-DATE-TIME:2023-10-24T01:00:15+09:00
#EXTINF:5,
https://media.radiko.jp/sound/b/LFR/20231024/20231024_010015_TK0pt.aac

fragments have b in their url, presumably that == type b
i downloaded m3u8s from type a, b, and c, no difference between them - bit-for-bit identical etc etc

tested with https://radiko.jp/#!/ts/LFR/20231024010000 (Adoのオールナイトニッポン) on radiko.jp-52 format, might be different for as-live formats
i have a hunch it might be for their dynamic ad insertion
only on phones apparently
maybe only v8? we’re using v7 no, screenshot shows v7
need to test with v8 wowza stream + v8 auth - need a way to save the whole as-live m3u8, might be annoying