lightspark/lightspark — comment on commit bf7c215b9b9c84de4904f1589c9a02b7b6eadf31
File:  line 0
By magcius:

Correct. While it's technically incorrect according to the SWF spec, the Flash Player does a lot of SWF repair tricks - if they see an unknown symbol in a control tag, they halt execution until they get the dictionary symbol that defines it.