What does "not support LTV" mean?

Question

I am using iText 5.5.3 for signing and timestamping in PDF documents. It works very well. But I recently switched from Acrobat Pro X to XI, and now I see this new line:

the signature is not LTV enabled and will expire after <date>

I think this warns me that after this date the subscriber’s signature will be considered invalid, right? However, the signature properties tell me:

the signature includes an embedded timestamp : <date/time>
signature was validated as of the secure timestamp time : <same date/time>

Now I'm a little confused: since the signature was declared valid on a known and certified date, why will it become invalid in the future?

Answer 1

LTV (Long Term Validation) and PDF Signatures

LTV-enabled term

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