Digital signature Filter / SubFilter

Hi,

i have a question regarding the use of digital signatures.

As a filter value i am using

Now i need to create PDF/A compliant pdfs and i read somewhere that it is not recommended (or not compliant?) to use

'adbe.x509.rsa.sha1' (pkcs#1 format). Instead one of the other two should be used.

Now since SHA1 is too weak only 'adbe.pkcs7.detached' (pkcs#7 format) remains.

But what does the 'detached' stands for?

Does it mean that the digest or the certicate have to be stored in an extra file? (Similar to the xml signing mechanism: "Enveloping signatures are over   data within the same XML document as the signature; detached signatures are over data external to the   signature element.") ?

Thanks for clarifying,

ToM