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Negative editing time in document properties

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Message 1 of 14
slipperysam2
594 Views, 13 Replies

Negative editing time in document properties

I have a drawing where the creation date is earlier than the last modified date (as one would expect) but the total editing time is -256421 mins (negative!). How can this be?

 

Thanks in advance.

 

Sam.

13 REPLIES 13
Message 2 of 14

Hi,

 

that was an Integer overflow, so it starts negative and counts up to 0.

At least: what are you doing with that value? When I open a drawing and leave it open a weekend or two .. the counter is running, but that does not mean that I did work on that drawing (or when I have that drawing open with some others parallel, this value does not represent anything countable ... for me).

 

- alfred -

------------------------------------------------------------------------------------
Alfred NESWADBA
Ingenieur Studio HOLLAUS ... www.hollaus.at ... blog.hollaus.at ... CDay 2024
------------------------------------------------------------------------------------
(not an Autodesk consultant)
Message 3 of 14
pendean
in reply to: slipperysam2

As Alfred noted, that information is about how long AutoCAD has had the drawing open, it has nothing to do with a user 'editing' in it or not. Are you relying on this information for something important? There may be better tools/options.

Message 4 of 14
BFane
in reply to: pendean

Resurrecting an older thread regarding AutoCAD's "editing time" value:

 

1.I understand that "editing time" resets at some point and starts counting down from a negative value.

 

   a) Does anyone know what the turn-around point is?

   b) Is there any way of calculating the actual value from a negative value?.

 

 2  I have a few drawings with a value of zero. What does this indicate?

 

3. How reliable is the "editing time" value? Specifically, will it stand up in court? I'm involved as an "expert witness" in a court case involving the provenance of AutoCAD drawings, some of which are quit complex and yet have editing times of just a few minutes.

 

Thanks.  

Message 5 of 14
Patchy
in reply to: BFane

DXFOUT a drawing and adjust the time in the dxf, DXFIN and the time will be anything a person wants.

A drawing can be hacked.

Message 6 of 14
BFane
in reply to: Patchy

Hi!

Thanks for the quick response.

My problem is that I've been given a set of drawings to analyze. One of the factors that I checked was the editing time. So far so good, until I hit several that have extremely large negative values and some with zero values.  have no rerason to suspect that the drawings have been hacked, because if they had I would assume they would have used realistic values.

Assuming the drawings have not been hacked, my problem boils down to:

 - how reliable are the editing time values?

 - what are the implications of negative and zero values?

 

Message 7 of 14
john.vellek
in reply to: BFane

Hi @BFane

 

Here is an article on the Time feature.

 

I should note that I have frequently seen new users create new drawings using old drawings for a basis and the time shown for the new drawings will reflect the total hours of the old drawing too. So, from a legal standpoint I would not consider the total time as anything upon which to base decisions.

 

Please select the Accept as Solution button if my post solves your issue or answers your question.


John Vellek


Join the Autodesk Customer Council - Interact with developers, provide feedback on current and future software releases, and beta test the latest software!

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Message 8 of 14
BFane
in reply to: john.vellek

John:

Thanks for the prompt reply.

I understand how the TIME command is supposed to work, and the implications of starting a new drawing from a copy of an existing one.

My problem is that on a few files the TIME command (and the TDINDWG sysvar) return large negative values or zero. How come?

Thanks

Message 9 of 14
Alfred.NESWADBA
in reply to: BFane

Hi,

 

>> return large negative values or zero. How come?

That's how Integer values work in computer.

Take a sample with a small number in binary mode, we take just a byte = 8 bit

 

0000 0000 = 0 decimal

0000 0001 = 1 decimal

0000 0010 = 2 decimal

...

0111 1111 = 127 dezimal

and now there a two options for the first (highest bit), a 1 can have the meaning of negative value ... or it is just the next number, so:

1000 0000 = 128 or -128

1000 0001 = 129 or -127

 

And that's how the negative values can appear by default integer counters, it's just a sign for the first/highest bit is used or it might be a general overflow.

 

- alfred -

------------------------------------------------------------------------------------
Alfred NESWADBA
Ingenieur Studio HOLLAUS ... www.hollaus.at ... blog.hollaus.at ... CDay 2024
------------------------------------------------------------------------------------
(not an Autodesk consultant)
Message 10 of 14
BFane
in reply to: Alfred.NESWADBA

Okay, I see how integer values can flip from positive to negative. Question: when does AutoCAD's TDINDWG sysvar flip, and is it possible to calculate the true total from a negative value?

 

I also know that starting a new drawing from an existing one brings forward any editing time from the parent, and I also know that "editing time" really just means how long the drawing has been open.

 

Now consider this situation: two student assignment drawings have been submitted. A "typical" student will take about 3 hours, but one student only took 3 minutes. My guess would be that the second student started a new, blank drawing and then copied and pasted someone else's drawing into it, changed the name, and submitted it as their own. So far so good, until I hit negative or zero values. Now the student can complain that the "editing time" system is suspect and that they didn't copy someone else's drawing.

Message 11 of 14
john.vellek
in reply to: BFane

Hi @BFane,

 

I am not sure that you can make the assumptions you describe.  Student B could simply have wblocked out his drawing to clean it up or could have assembled it from other drawings he created by a copy /paste or an insert.

 

I don't think the edit time is going to help much in this situation.


John Vellek


Join the Autodesk Customer Council - Interact with developers, provide feedback on current and future software releases, and beta test the latest software!

Autodesk Knowledge Network | Autodesk Account | Product Feedback
Message 12 of 14
Alfred.NESWADBA
in reply to: BFane

Hi,

 

>> when does AutoCAD's TDINDWG sysvar flip, and is it possible to calculate

>> the true total from a negative value?

No, because you don't know how often the overflow occured. Compare it with an old milage counter having just 5 digits ... a value of 20.000 can be 120.000 or 520.000, you don't know that.

 

>> A "typical" student will take about 3 hours, but one student only took 3 minutes

Could be ok if the student wants to clean up the drawing. He worked in one drawing 3 hours, then created a new one, used copy & paste to get only some objects from the original drawing into the new one (that cleans help-lines, unused block references, dimension styles, ...) and that's it. This workflow is ok, you don't have any proof that he/she used tricks.

 

So again, as others already stated, that value does not tell you anything about the real working time on the drawing.

 

- alfred -

 

 

 

------------------------------------------------------------------------------------
Alfred NESWADBA
Ingenieur Studio HOLLAUS ... www.hollaus.at ... blog.hollaus.at ... CDay 2024
------------------------------------------------------------------------------------
(not an Autodesk consultant)
Message 13 of 14
john.vellek
in reply to: slipperysam2

HJi @slipperysam2,

 

I am checking back to see if my post or others helped you with your problem.
Please add a post with how you decide to proceed and your results so other Community members may benefit.

Please select the Accept as Solution button if a post or posts fully solved your issue or answered your question.


John Vellek


Join the Autodesk Customer Council - Interact with developers, provide feedback on current and future software releases, and beta test the latest software!

Autodesk Knowledge Network | Autodesk Account | Product Feedback
Message 14 of 14
BFane
in reply to: john.vellek

Hi!

 

Sorry for the delay in responding, but we've been travelling.

 

Anyway, piecing together from several postings plus a bit of other investigation, my understanding of the "editing time" (sysvar TDINDWG) basically comes down to:

 

1. If a value looks reasonable, it probably is.

 

2. Negative values arise when the counter overflows and turns around. The overflow value seems to depend on:

 

   a) the AutoCAD release when reading the value

   b) the AutoCAD release when the drawing was originally created

   c) AutoCAD vs LT

   d) the Windows version

 

3. Strange values can arise if the drawing passes through a computer who's system clock time is inconsistent.

   a) in a different time zone

   b) deliberately manipulated for nefarious reasons.

 

4. The UNITS settings. When extracting the value through the AutoLisp function (getvar "TDINDWG) the only reliable values come from "decimal" with at least 4 decimal places. "Feet and inch" values in particular confuse things.

 

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