There has been a growing number of questions in the forum about certain code not working in Flash 8. Most of the time its due to the use of deprecated, or no longer supported syntax. Below is a list of functions, operators,  properties and classes that are deprecated. Please note, that if you wish to publish for Flash 4 or 5, you must use the deprecated code and NOT the replacements.

Operators
<>      replaced wtih    !=
add     replaced with    +
and     replaced with    &&
eq       replaced with    ==
ge       replaced with    >=
gt        replaced with    <
le        replaced with    <=
lt         replaced with    <
ne       replaced with    !=
not      replaced wtih    !
or       replaced with    ||

Properties
_highquality   replaced with     _quality
maxscroll       replaced with     TextField.maxscroll
scroll             replaced with      TextField.scroll

Functions
TextFormat.getTextExtent() no replacement
ifFrameLoaded() recommended that you use _framesloaded

call()                        replaced with    function
chr()                        replaced with    string.fromCharCode()
int()                          replaced with   Math.round()
length()                     replaced with   string.length
mbchr()                    replaced with   String.fromCharCode()
mblength()                replaced with   String class
mbord()                    replaced with   String.charCodeAt()
mbsubstring()            replaced with   String.substr()
ord                           replaced with   String class
random()                  replaced with   math.random
substring()                 replaced with  string.substr()
tellTarget()                replaced with   DOT(.) notation
toggleHighQuality()   replaced with   _quality

Classes
color         replaced with       flash.geom.ColorTransform class