INT 2F C - NLSFUNC.COM - INSTALLATION CHECK
        AX = 1400h
Return: AL = 00h not installed, OK to install
             01h not installed, not OK
             FFh installed
Notes:  this function is called by the DOS v3.3+ kernel
        supported by OS/2 v1.3+ compatibility box, which always returns AL=FFh
        supported by DR-DOS 5.0
        documented for MS-DOS 5+, but undocumented in prior versions
SeeAlso: AX=1401h"NLSFUNC",AX=1402h"NLSFUNC"

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