How to create a pdf/a-1b with a text field

Question

hello, I'm trying to execute a very simple task: create a pdf/a-1b containig a text field.
using Acrobat XI pro, I created a simple pdf form with 1 form field of type text , then tried to save as pdf/A-1b. The pdf is saved but the form field is removed from resulting pdf.
Here in detail the steps I made:
0) configure adobe pdf printer to save as pdf/A-1b
1) creat a test.txt with notepad
2) print using acrobat pdf printer
3) open the generated pdf with Acrobat XI
4) in 'Standards' panel I see that pdf conform
5) now go to 'Tools\Modules' and 'Modify'
6) add a textbox field
7) exit from 'Modify' mode and save
8) in 'Standards' panel I see that pdf doesn't conform.
9) I opened the preflight tool and see two errors
     a) "XMP property for a page object not predefined and no extension schema present".
     page reports the following Trigger values:
     - Extension schema is present in XMP: is not true
     - Property exists in PDF/A Standard: is not true
     b) Form field does not have an appearance dictionary
     page reports the following Trigger values:
     - Form field has an appearance dictionary: is not true
I'm quite new to Acrobat: simply downloaded the Actobat XI evaluation version, created the file and added the text field. No special settings nor other configurations was applied,
I'm wondering if someone else was able to reproduce this behavior.
thank you for any comment

Answer 1

First, about invalidating the PDF/A. I was told, but never had this confirmed nor tested, that editing a PDF/A will automatically cause the PDF/A status to be deleted from the file. This is because Acrobat does not know about the compatibility of every edit with every current (and future) PDF subset standard, so it is safest just to remove the indicator - if you turn off Adobe's PDF/A view mode which will prevent editing anyway.
Now, you have a problem with the signatures. Possibly a very big one. Your description "2) fill the text field with some annotations and then sign the signature field 3) save the pdf" is a little too separated. At the time a file is signed it is saved, the hash calculated, and written to the file. So signing and saving are just one action. Yet an unsigned digital signature needs, it seems to me, no appearance.
I think the solution is a simple one. Sign it, but not with a signature field. If it is PDF/A when you start it is probably PDF/A when you finish. Signature fields seem a distraction and obstacle to the important thing, signing.