as.declared             Labelled vectors with declared missing values
as.haven                Coerce to haven / labelled objects
declared_package        Functions for Declared Missing Values
drop_undeclare          Drop information / undeclare labelled objects
is.empty                Test the presence of empty (undeclared) missing
                        values
labels                  Get / Declare value labels
measurement             Get / Set measurement levels for declared
                        objects
missing_range           Get / Declare missing values
w_IQR                   Compute weighted summaries for declared objects
