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DoABC

Tag Info
Tag Number: 
82
Tag Type: 
Action
Tag Flash Version: 
9
Unknown SWF Tag: 
This tag is defined by the Flash documentation by Adobe
Brief Description: 

New container tag for ActionScripts under SWF 9. Includes an identifier, a name and actions.

Tag Structure: 

Tag Structure: 
struct swf_doabc {
	swf_tag			f_tag;		/* 72 or 82 */
	if(f_tag == DoABC) {
		unsigned long	f_action_flags;
		string		f_action_name;
	}
	swf_action3		f_action_record[variable];
};

*the version specified here is the version in which the tags appeared—however, actions of higher versions can be used with older version tags and thus this version doesn't indicate the version of all the actions used in this tag

The DoABC and DoABCDefine are available since version 9. These are similar to the old DoAction and DoInitAction, yet the actions use a way different declaration scheme and they include flags and a name. This new scheme helps greatly in simplifying the definitions of ECMAScript classes and accelerate the access to the code tremendously.

Note that the f_allow_abc bit of the FileAttributes flags must be set for the ABC actions to work at all.

The following describes the data in the DoABC and DoABCDefine tags. Note that at this point the DoABCDefine tag is not available, probably because you can do the same thing with a DoABC.

The f_action_flags define one bit at this point: bit 0 is kDoAbcLazyInitializeFlag. All the other bits must be set to zero to ensure forward compatibility. The lazy initialization bit is used to determine whether the DoABC tag is in place (execute as encountered) or callbacks (execute as it is referenced by other scripts.)

The f_action_name represents the name of this action script in case of a DoABC.

In some document, it mentioned that it would represent the name of a class when the DoAction3Instantiate tag is used. However, that tag is not implemented yet if ever.

The f_action_record is a buffer of action script version 3. It is different from the DoAction action script and is called the ABC script.

At this time, the swf_action3 is badly documented in the abcFormat.html file. There are now much better documents about this format on the Mozilla website.

Comments

Tag ID is not 82

I think you mixed DoABCDefine with DoABC. The spec says DoABC is 0x82 (and doesn't mention DoABCDefine).

The ID listed under http://www.m2osw.com/swf_tag_doabc is wrong.

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