VI Modification Bitset - Bit interpretation

[Bernd]

Hello to all the forum users,

i have a VI and after stoping this vi there is a "VI modification Bitset"-property node. Its value is checked for 0 in a case structure. If 0 then close LabVIEW. If not, ask for save.

I see "0" means "no changes". I understand this.

After running in LV8.2 there is no "*" in the title-bar, so i think there is no change made, but if i close the VI there comes a popup to save changes. So i checked the "VI modification Bitset" is something like 0x18000000(U32).

I found the information, there was a change at LV8.5/LV8.6. Now (LV2011) this value is U64.

But i did not find some information about interpretation of the Bits.

If i can ignore this bits i can close LV, too, but i dont want to close LV if i don`t know why this value is not = 0.

Thanks for your help.

Bernd

[Rolf Kalbermatter]

Hello to all the forum users,

i have a VI and after stoping this vi there is a "VI modification Bitset"-property node. Its value is checked for 0 in a case structure. If 0 then close LabVIEW. If not, ask for save.

I see "0" means "no changes". I understand this.

After running in LV8.2 there is no "*" in the title-bar, so i think there is no change made, but if i close the VI there comes a popup to save changes. So i checked the "VI modification Bitset" is something like 0x18000000(U32).

I found the information, there was a change at LV8.5/LV8.6. Now (LV2011) this value is U64.

But i did not find some information about interpretation of the Bits.

If i can ignore this bits i can close LV, too, but i dont want to close LV if i don`t know why this value is not = 0.

Thanks for your help.

Bernd

The meaning of this bitset is private to LabVIEW and undocumented. As such it is also highly susceptible to changes and completely incompatible reeinterpretations between LabVIEW versions.

Some of the more trivial modifications like front panel or diagram changes can be quite easily deduced but there are many obscure modifications in LabVIEW that get recorded in this bitset that nobody without access to the LabVIEW source code could ever guess.

Try to look in the VI Properties->Current Changes dialog and see what it mentions there. You might be able to deduce some of these bitflags from there, but quite a few bitflags are lumped together in more common modification reasons.

[crelf]

If you ever do work out the pattern, it'd be nice if it was added to the LabVIEWwiki.org.

[Rolf Kalbermatter]

If you ever do work out the pattern, it'd be nice if it was added to the LabVIEWwiki.org.

While I have some basic information about this in earlier LabVIEW versions (v5), I'm hesitant to publish that since there are certainly differences in LabVIEW versions. I don't have the details about this but I remember having to abandon some code in newer versions that was relying on these bits having certain meanings.