timestamp issue

[tschmidtb51]

The current (and proposed in #25) spec violates the rule

[doc_time_first_isued] MUST equal the oldest [statement_time_first_issued] of all included VEX statements.

in the second example given in section Updating Statements with Inherited Data.

See also #29

[puerco]

Mmh I think this is one to take back to the wide VEX-WG. In my opinion this assertion is wrong:

[doc_time_first_isued] MUST equal the oldest [statement_time_first_issued] of all included VEX
statements.

While cascading the date from the document to the statements allows for more compact statements and less redundancy, a document should be able to be created at anytime containing VEX statements formulated in the past.

[puerco]

Tagging @zmanion for some perspective here