Metadata version 1.2 has two main updates with respect to the
metadata version 1.1 (EHTC_metadata2018_Dec2023.tar.gz)
described in section 6.3.1 of the EHT 2018 memo[1]:

1) We recalculated SEFDs for SMA following the approach by Lu+2013[2].
This will be described in an upcoming EHTC memo that accompanies the
release of metadata from the 2021 campaign.

2) New ALMA tables posted as Rev7-Meta which correct polarization conversion
errors on sub-bands of tracks e18c21(b2 and b3), e18c25(b2), and e18g27(b3).

Since this version 1.2 was made with new raw metadata (from ALMA), the
version inside the "raw" folder changed from v1.0 to v1.1. Additionally,
the folder "aux" is now named "ancillary". This helps avoid conflict with
some systems which prevent extracting tarballs with contents named "aux".

[1] https://eventhorizontelescope.org/files/eht/files/eht_memo_koay_2023-l1-01.pdf
[2] https://iopscience.iop.org/article/10.1088/0004-637X/772/1/13