We are not aware of a specific statement regarding the change, but it is evident in the data and in table titles in the associated press release (citation).

In response, we have:

1. Achieved the predecessors (currency reference year 2011, 1995Q1 to 2019Q2) by renaming with an "_11" specifier, marking metadata as "discontinued", and segregating in the catalog. 
2. Created one-for-one replacements (reference 2016).
3. Replaced the current-value series in the same way, as they may be subject to revisions apart from the reference year.
4. Transplanted global concept aliases.
5. Refurbished the catalog.

Notable properties (for full list, see Mnemonic 411):

• Currency reference year: Changed from 2011 to 2016
• Start date: Unchanged
• Series count: Unchanged

The series reside in the historical catalog: 

• Portugal » National Accounts » by Expenditure » Quarterly
• Portugal » National Accounts » by Expenditure » Quarterly » Discontinued » Ref 2011
• Portugal » National Accounts » by Value Add » Quarterly
• Portugal » National Accounts » by Value Add » Quarterly » Discontinued » Ref 2011