How to properly format last modified (lastmod) time for xml sitemaps

Question

I am creating an app that will automatically update sitemap.xml each time new content is added to, or updated on the site.

According to Google\'s best pract

Answer 1

The format for the lastmod field in Google Sitemaps XML for C# is the following:

var lastmod = DateTime.Now.ToString("yyyy-MM-ddTHH:mm:sszzz");

It provides values such as 2018-08-24T09:18:38-04:00 which is the W3C Datetime format.