From: Derrick Stolee <stolee@gmail.com>
Date: Fri, 22 Jun 2018 18:32:56 GMT
Subject: Re: [PATCH 09/23] midx: write pack names in chunk
Message-ID: <d79e4b0f-eeaa-0995-1ee6-8565903f2899@gmail.com>
In-Reply-To: <xmqqzhzmptab.fsf@gitster-ct.c.googlers.com>

On 6/22/2018 2:31 PM, Junio C Hamano wrote:
> Derrick Stolee <stolee@gmail.com> writes:
>
>> The index extension documentation doesn't appear to be clear about
>> which extensions are optional or required, but it seems the
>> split-index is the only "required" one and uses lowercase for its
>> extension id.
> read-cache.c::
>
>      /* Index extensions.
>       *
>       * The first letter should be 'A'..'Z' for extensions that are not
>       * necessary for a correct operation (i.e. optimization data).
>       * When new extensions are added that _needs_ to be understood in
>       * order to correctly interpret the index file, pick character that
>       * is outside the range, to cause the reader to abort.
>       */

Thanks! I was reading Documentation/technical/index-format.txt and 
optional extensions are mentioned but not described precisely.