In linear regression the least squares (LS) has variant versions according to the error configuration such as total least squares, data least squares (DLS), constrained or structured TLS and so on.
The least squares (LS) has variant versions according to the error configuration such as total least squares. This was in linear regression. The least squares (LS) has constrained. This was in linear regression. The least squares (LS) has structured TLS and so on. This was in linear regression. Total least squares are data least squares (DLS).