Function calls in PL/SQL are quite verbose.
In a plain SQL query, we can do this…
sde.st_geometryN_f(shape,1)
…but in a custom PL/SQL function, we have to do this:
sde.st_geometry_operators.st_geometryN_f(shape,1)
Which makes the function calls hard to read when we string multiple functions together:
-- startpoint X of a multi-part polyline
sde.st_geometry_operators.st_x_f(sde.st_geometry_operators.st_startpoint_f(sde.st_geometry_operators.st_geometryN_f(shape,1)));
More info: Use SDE.ST_GEOMETRY functions in a custom function
Could Esri give us a shorter way to make SDE.ST_GEOMETRY function calls in PL/SQL?