What does this syntax mean? “yyy(1,1) logical = xxx”

I found such a syntax in the class definition of the built-in toolbox, but I don't know what it means.

What is the syntax? What does it mean?

Where can I find a comprehensive grammar explanation?

What does "(1,1)" mean?

What does "logical" stand for?

IsEarthCentered(1,1) logical = trackingScenario.DefaultIsEarthCentered;

Answer 1

[Walter Roberson]

It is a property name, size, datatype, and initial value.

Answer 2

[Steven Lord]

See this documentation page for information about the property validation syntax used in properties blocks inside a classdef file.

This line:

IsEarthCentered(1,1) logical = trackingScenario.DefaultIsEarthCentered;

means that any value you assign to the IsEarthCentered property must be a scalar (1-by-1) value that is logical or can be converted to a logical. If you don't set it, the default value of that property is the value of (what I suspect to be a Constant property of the trackingScenario class, based on the name) trackingScenario.DefaultIsEarthCentered.