Inside Guarantee (IS) Question

[brilliantseas]

Looking at a Carnival Venezia booking in February and it appears as if all categories are sold out except for 1A Upper/Lower and IS Inside Guarantee.

 

My question is, does Carnival consider category 1A a part of the "Inside Guarantee" categories, or does category IS (Inside Guarantee) include only 4A or higher? 

[Elaine5715]

It includes 1As