Special Tickets (generally, not fully available to all USA residents at all times.)
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Military Tickets -
These are tickets similar to MYW tickets and can be sold at various military bases and at the Shades of Green Resort at WDW.
These Military Tickets are not only price-discounted, but Florida Sales Tax is not charged.
Military "Non-Salute" Tickets can be upgraded similarly to regular MYW tickets.
They can be "price bridged" to the current gate price of the equivalent ticket.
These are subject to the same rules as MYW ticket upgrades:
Must be done within 14 days of first use and with entitlements still remaining on the ticket.
Military "Salute" Tickets can only be upgraded in limited ways.
There's a 5 day option this year, so someone with a 4 day Salute ticket can add the extra day. They can also add either option they didn't already have (PH or WPF&M).
This can be done up until the ticket is expired, regardless of entitlements remaining.
Any of the military tickets, Salute or not, can be upgraded to an AP.
But, the Salute tickets only get price bridged to their own equivalent gate price, with tax included - not to the full price of a regular 4 or 5 day PH/WPF&M.
If any WPF&M entries have been used, the ticket can only be upgraded to the Platinum Plus pass.
Some military tickets have been subject to blackout dates.
It appears that at least for the rest of 2017, there are no blackout dates, and
that valid admission dates run through December 19, 2017.
Ticket purchases are generally considered to be "non-refundable."