Why is the Class field greyed out at the line level of the vendor bill form?

AI generated answer (using internal Slack threads):

The Class field at the line level of the vendor bill form can be greyed out due to several reasons. One of the common reasons is that the 'Match Bill to Receipt' option is not activated. If this option is not ticked, the system will not allow you to associate the correct receipts to the line for posting vendor bill variance, hence the field will be greyed out. Another reason could be related to the system-generated fields. Fields like Tax Code, Tax Rate, Tax Amt, and Gross Amt are system-generated and cannot be populated directly. They are calculated at the time of transaction and are populated via Sales Orders (SO's) and Purchase Orders (PO's). If you are trying to populate these fields directly, they will be greyed out. Lastly, the visibility of certain fields can also depend on the functionalities enabled in your NetSuite account. For instance, if you do not have SuiteTax enabled, US purchases will not have a tax component and the tax fields will be greyed out. ****** Disclaimer: This response was generated by an artificial intelligence assistant based on previous conversations from multiple Slack channels, and may contain inaccuracies or mistakes. ******