Two-level sitemap index -- is it possible?

Question

Search Engine Optimization

The specification on sitemaps ( www.sitemaps.org/) says:

If you need to list more than 50,000 URLs, you should create multiple Sitemaps. If you need to upload multiple Sitemaps, you must list each of these files in the Sitemap index file. A maximum of 50,000 Sitemaps can be listed in a Sitemap index file.

Is it possible to make an index double nested?
For example:
//mysite/sitemap.xml

<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
    <sitemap>
        <loc>http://mysite/storage/sitemaps/index.xml</loc>
        <lastmod>2004-10-01T18:23:17+00:00</lastmod>
    </sitemap>
</sitemapindex>

//mysite/storage/sitemaps/index.xml is:

<?xml version="1.0" encoding="UTF-8"?>
<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
    <sitemap>
        <loc>http://mysite/storage/sitemaps/sitemap-lm.xml.gz</loc>
    </sitemap>
    <sitemap>
        <loc>http://mysite/storage/sitemaps/sitemap-1.xml.gz</loc>
    </sitemap>
   ....
</sitemapindex>

well , //mysite/storage/sitemaps/sitemap-lm.xml.gz is already a normal XML file (passing validation and so on). There is no definitive answer
in the specification . On stackoverflow too. And Google and colleagues give ambiguous and unreliable answers - from “it’s possible, why not” to “no, it’s impossible for someone to do something like that” Dear toaster, is it possible or not? Has anyone done this?

Answer 1

Posted on stackoverflow:
stackoverflow.com/questions/37215727/multi-tiered-...

Answer 2

You can definitely do multi-level sitemaps.
Here is an example on the client's site bulat.ua/sitemap.xml - the first level refers only to the second level sitemaps.

Answer 3

Yes, and your version shouldn't be a problem. At least you can add google to webmaster and after a short time it will show which files it read.
What is the purpose of double nesting? Look at this option: ru.evelito.com/sitemap/sitemap.xml
It has been indexed by more than 30% (in total there are 2.550.000 links) for more than a month.
It is not necessary that the main file be at the root. Just add it to robots.txt or search engine webmaster panel and that's it.

<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
<sitemap>
<loc>https://evelito.com/sitemap/sitemap-cc-ru-10.xml.gz</loc>
<lastmod>2019-08-04T06:08:04+03:00</lastmod>
</sitemap>
<sitemap>
<loc>https://evelito.com/sitemap/sitemap-cc-ru-27.xml.gz</loc>
<lastmod>2019-08-04T06:08:04+03:00</lastmod>
</sitemap>
<sitemap>
<loc>https://evelito.com/sitemap/sitemap-cc-ua-3.xml.gz</loc>
<lastmod>2019-08-04T06:08:04+03:00</lastmod>
</sitemap>
</sitemapindex>