$2\mathrm{.}2$ Explain the following codes.

$(10)$

$2\mathrm{.}2\mathrm{.}1$ GDS $(7)$

$2\mathrm{.}2\mathrm{.}2$ CRS $(3)$

$2\mathrm{.}3$ Briefly explain the following terminology in the Travel Industry and give the passengerrelated codes:

$2\mathrm{.}3\mathrm{.}1$ Adult $(3)$

$2\mathrm{.}3\mathrm{.}2$ Child $(3)$

$2\mathrm{.}3\mathrm{.}3$ Infant $(4)$

$2\mathrm{.}4$ Give the applicable code for the following classes of travel:

$(5)$

$2\mathrm{.}4\mathrm{.}1$ Business class

$2\mathrm{.}4\mathrm{.}2$ Coach economy

$2\mathrm{.}4\mathrm{.}3$ First class

$2\mathrm{.}4\mathrm{.}4$ Business class premium

$2\mathrm{.}4\mathrm{.}5$ First class premium