Вроде да, но с особенностями
https://docs.microsoft.com/en-us/dyn.../xpp-operators
Tables
All tables inherit directly from the Common system table, unless they explicitly inherit from a different table. The Common table can't be instantiated. It doesn't exist in the underlying physical database. The Common table inherits from the xRecord class, but in a special way that isn't appropriate for the is keyword or the as keyword. When the as keyword is used to perform an invalid downcast among tables, the target variable references an unusable non-null entity. Any attempt to de-reference the target variable will cause an error that stops the program.
The is and as keywords and extended data types
Each extended data type has an Extends property. The style of inheritance that this property controls differs from the style of inheritance that the is and as keywords are designed for.