David Clipsham

Just created some test files, as attached. DROID confirms its behavour as equivalent to !FE && !FF  [Should_be_nope_FEFF.txt](https://github.com/digital-preservation/droid/files/9377581/Should_be_nope_FEFF.txt) [Should_be_yep_AA00.txt](https://github.com/digital-preservation/droid/files/9377582/Should_be_yep_AA00.txt) [Should_be_yep_AAFF.txt](https://github.com/digital-preservation/droid/files/9377583/Should_be_yep_AAFF.txt) [Should_be_yep_FE00.txt](https://github.com/digital-preservation/droid/files/9377584/Should_be_yep_FE00.txt) [Should_be_yep_FEAA.txt](https://github.com/digital-preservation/droid/files/9377585/Should_be_yep_FEAA.txt) [Should_be_yep_FF00.txt](https://github.com/digital-preservation/droid/files/9377586/Should_be_yep_FF00.txt) NB these are just skeleton files...

Not me I don't work for them any more :) But it's clear fmt/142 isn't working as intended and that there'll be false negatives that are ID'ing as fmt/6 as...

Cool - worth exploring for sure, thank you. Sorry for derailing the [!10] inversion issue!

Looking at fmt/142 in the context of related formats: fmt/141: `52494646{4}57415645666D7420100000000100{14-*}64617461` (chunk length == 10 (exactly 16 bytes) and wformat tag == 01) fmt/142: `52494646{4}57415645666D7420[!10]{3}[!FEFF]{16-*}64617461` (chunk length != 10 and...

Thanks Steve, from the signature descriptions on PRONOM itself, fmt/141 is assuming chunk size of 16, fmt/142 is assuming 18+, fmt/143 is assuming 40+ so I believe those assumptions hold...

I'm in the process of creating a minimal signature file and skeleton test files - shouldn't take long

Proposed alterations seem to work - new sig for fmt/142 created with http://ffdev.info/ and used existing sigs for fmt/141 and fmt/143 in minimal sig file as attached, adding fmt/143 priority...

Unless anybody finds any other issue with the above, I'll submit a request to PRONOM team to update sig for fmt/142 and priority for fmt/143 this afternoon

Oh crikey, check out the signature for x-fmt/223 - https://www.nationalarchives.gov.uk/PRONOM/Format/proFormatSearch.aspx?status=detailReport&id=315&strPageToDisplay=signatures Sig description: Identifier (0x1991), width of image not equal 320, height of image not equal to 200, X offset not...

full list of use of !byte-sequence patterns, accurate to v107: x-fmt/223 - `1991[!4001C80000000000]` fmt/142 - `52494646{4}57415645666D7420[!10]{3}[!FEFF]{16-*}64617461` x-fmt/12 - `31BE000000AB0000000000000000{82}[!0000]` x-fmt/4 - `32BE000000AB0000000000000000{82}[!0000]` and then these formats use [!00] (for which...