A recovery window is a period of time that begins with the current time and extends backward in time to the point of recoverability. The point of recoverability is the earliest time for a hypothetical point-in-time recovery, that is, the earliest point to which you can recover following a media failure. For example, if you implement a recovery window of one week, then this window of time must extend back exactly seven days from the present so that you can restore a backup and recover it to this point. You implement this retention policy as follows:
這段是ORACLE ONLINE DOC上面的一端，假如，我的WINDOW設置為7天，以前一直以為在最近7天內的備份資料都保存在CATALOG中，并且不會是OBSOLETE狀態，但是，看了這一段話之后，覺得的理解好象有問題，大家發表一下自己的看法
