Blocs css file

When I open a Blocs file you see the linked stylesheets (style.css). However the Blocs stylesheet (and others) show style.css?xxxxx. Why the ?xxxxx? What does it do?
It appears that if you remove the ?xxxxx does not alter the webpage.

Hey @Johndw

You have Cache burst select for export. More info here

https://blocs3-help.blocsapp.com/knowledge-base/project-settings/#cache-bust-css-and-js