What makes annotations special?

Symbology

Unlike standard geometry (points, lines, areas), symbology is stored in the feature class for annotations.

An annotation usually belongs to an annotation class (subtype). This annotation class is assigned a symbol ID (attribute SymbolID) for standard presentation.

When created, an annotation feature is assigned a symbol ID. The layout parameters of the standard presentation can be changed (e.g. using the attribute editor). Any change from the standard is stored in a BLOB field for the feature. In addition, the changed property is noted in the attribute Override (bit pattern).
 

Layout parameter attributes

The layout parameter attributes displayed in the database are only a copy of the layout parameters stored in the BLOB field! Only the BLOB field is effective. Manipulating the copy attributes leads to confusion.

The attributes Textstring, SymbolID and Override are not copy attributes and are therefore not present in the BLOB field.
 

Inline annotations

Inline annotations are annotations that have all their layout parameters stored in the feature (in the BLOB field). This means that they do not use the default presentation stored for the annotation class.
They therefore require slightly more storage space than normal annotations.
They often arise in the context of data migration or data import. UT functions do not generate inline annotations.
Inline annotations can be recognised by the fact that their symbol ID has the value -1.
 

Useful links

What is annotation?
Managing annotation feature class properties
Editing the attributes of annotation