I did it! Script to compute UNIX time!

RouterOS Scripting
18

search tag # rextended lowercase uppercase chr2lcase chr2ucase

Functions to convert single character on lowercase and to uppercase.
Any other character passed remain unchanged.

:global chr2lcase do={
    :local charsString ""
    :for x from=0 to=15 step=1 do={ :for y from=0 to=15 step=1 do={
        :local tmpHex "$[:pick "0123456789ABCDEF" $x ($x+1)]$[:pick "0123456789ABCDEF" $y ($y+1)]"
        :set $charsString "$charsString$[[:parse "(\"\\$tmpHex\")"]]"
    } }
    :local chrValue [:find $charsString $1 -1]
    :if (($chrValue > 64) and ($chrValue < 91)) do={
        :return [:pick $charsString ($chrValue + 32) ($chrValue + 33)]
    } else={
        :return $1
    }
}

:global chr2ucase do={
    :local charsString ""
    :for x from=0 to=15 step=1 do={ :for y from=0 to=15 step=1 do={
        :local tmpHex "$[:pick "0123456789ABCDEF" $x ($x+1)]$[:pick "0123456789ABCDEF" $y ($y+1)]"
        :set $charsString "$charsString$[[:parse "(\"\\$tmpHex\")"]]"
    } }
    :local chrValue [:find $charsString $1 -1]
    :if (($chrValue > 96) and ($chrValue < 123)) do={
        :return [:pick $charsString ($chrValue - 32) ($chrValue - 31)]
    } else={
        :return $1
    }
}

:put [$chr2lcase "A"]

:put [$chr2ucase "a"]