$($a$)$ Explain all the definitions of HL $7$ and limitations of $2\mathrm{.}5$ version of HL $7.$

$($b$)$ Decode the following HL $7$ codes.

$MSH{|}^{{?}^{{?}^{?}}}|$&$||OTHER$ REG MED

$CT{R}^{{?}^{{?}^{?}}}{1234567890}^{{?}^{{?}^{?}}}\frac{N}{P}$I $||201102171658||AD{T}^{{?}^{{?}^{?}}}A{01}^{{?}^{{?}^{?}}}AD{T}_{A}01|2011021716|58076|P|2\mathrm{.}3\mathrm{.}1$

EVN$||201102171658$