Value in Marketo

[o_aksu]

Hi All, 

I just have a very simple question, what is an AIL value in marketo ?

[cookiemonstersa]

I don't think that's a standard field. You can see the list of standard fields here: https://developers.marketo.com/rest-api/lead-database/fields/list-of-standard-fields/

Probably a custom field that is syncing over via your CRM or someone before you created it in Marketo. 

I would ask whoever runs your CRM. Often you'll find outdated or graveyard fields exist within Marketo and CRMs.