VBR & COVER Fields

When song tags are displayed in Mp3tag, there are a couple of fields / columns that I do not understand.

What is the purpose of the VBR field? For all of my songs, I notice it has a value of CBR or blank. What is it used for? I can't find its definition in the ID3v2 tag definition.

Same question for the COVER field. For my songs it has a value of blank, 1, 2 or 3. What is it used for and what do the values mean?

Thanks

The VBR technical field shows whether the file is encoded using Constant Bit Rate (CBR) or Variable Bit Rate (VBR). This information is not queried from the tag but from the actual audio data of the file and is only available for some audio formats.

The cover field is a technical field which simply shows the number of embedded cover art in the file's tag.

Most of the fields are explained in Mp3tag's help file at Customizing the file list columns.

Kind regards,
Florian

Vielen Dank!