5.1.9 ‘Q’ exponent-letter

GNU Fortran accepts real literal constants with an exponent-letter of ‘Q’, for example, 1.23Q45. The constant is interpreted as a REAL(16) entity on targets that support this type. If the target does not support REAL(16) but has a REAL(10) type, then the real-literal-constant is interpreted as a REAL(10) entity. In the absence of REAL(16) and REAL(10), an error occurs.