How to send an email using send email smartshape and choosing an specific attachment in the case

I’m trying to send an specific attachment in my case, I see the options to choose what attachments to send in the email and there is a drop down with two options available: either send all email on a category or a field. Documentation says “or select Field for a single attachment that is stored in the field that you provide” so isn’t clear to me what value is Pega expecting to find in the property we include in there so that it can send an specific attachment. is it the pzInskey of the attachment? the base64?

@CarlosV1753 It is not workobject or attachment keys, basically u need to pass the comma seperated category values in Field value. The code will go through the work object attachments and check only for those categories mentioned in the Comma seperated values.