There are only two reasons a field would not be available. The first is that the field is already on the Custom Panel. Since I'm sure this is not the case we'll go with door number two. The second reason is that the field does not exist.

You can check your custom field definitions in Preferences - General - Basic - Custom Fields. I saw your linked image before on my phone but it is no longer available??? Instrument and Period are not built in fields nor are they standard tags. They are used by some players such as Audirvana but not by others such as Roon. They must be created as Custom Fields. As these fields are used by Audirvana they are automatically imported along with Soloist, Style and Ensemble when the Audirvana Custom Editing panel is imported. As you're creating your own custom panel, I've uploaded the Custom Field definitions (without the custom panel). You can download:

https://2manyrobots.com/actions/AudirvanaCustomFields.zip

From the Yate menu do an Import Preferences and select the downloaded zip file. This will give you the fields mentioned above. You can also do it without downloading anything by going to Preferences - General - Basic - Custom Fields; select an unused custom field location; from the Choose commonly used mapping menu choose Period and then repeat for Instrument. (Careful there is also an Instrumental field).

Release Time and Release Date are the same. Yate uses Release Time simply because that's what it's called in the ID3 specification.

Title is a completely standard field type in all audio formats. Work Name is mapped to Apple's definition of a work name. In iTunes/Music you can flip a track's display between Title and Work Name. Some other players such as Roon use a Work field with different low level mappings.

Any saved custom panel can be used as a template for others. There are ten available custom panels which you can define. You can easily copy one custom panel to another as follows:

- select the new custom panel at the top right of the display.
- hit the Import/Export control at the bottom right and from the menu choose the panel you're copying from.

In the forum there is a Submit Quick Reply button and a Reply button. Reply allows you you to upload an image. Technically you can upload up to three images but the forum I'm using is very old and more or less unsupported. Changing the forum to something newer is a nightmare I'm trying to avoid. Uploading one image works well ... I do it all the time 🙂

There are only ten columns available to display Custom Fields in the File List panel. This is due to the fact that originally there were only five Custom Fields available and the capabilities just kept being expanded. You assign a Custom Field to a column where you design the Custom Fields. Preferences - General - Basic - Custom Fields.

Use the Associate with Column control to map the field to a column. Once you've done that the file list table header menu will be changed to include the field. They appear as Custom Column (name)

In the same configuration panel you can make custom fields popup fields so that they can have an associated list. Much as the Artist, Genre, etc. fields. Setting them as a popup makes the field list aware. You would do the list mapping in Preferences - Lists as you would any built in field.