There is no way to save down vertical content, API or otherwise, that actually converts vertical objects to an earlier version. The one caveat that I know of, is a *very* brief interval where several versions of Civil3D could cross-communicate for common objects.
Out of curiosity, what does it report that it's actually fixing in the DWG file?
If you are going to fly by the seat of your pants, expect friction burns.
"I don't know" is the beginning of knowledge, not the end.
More clearly this time: there is NO WAY to save vertical content to an earlier vertical version. Mechanical 2015 objects cannot be converted to Mechanical 2012 objects; Civil3D 2017 objects cannot be converted to Civil3D 2012 objects; Plant3D 2016 objects cannot be converted to Plant3D 2014 objects. Even if the DWG file version is changed to an earlier version, the content version of vertical objects stays the same. Otherwise there would be no complaints about backwards version compatibility for the vertical products. 
If you are going to fly by the seat of your pants, expect friction burns.
"I don't know" is the beginning of knowledge, not the end.
@dgorsman wrote:More clearly this time: there is NO WAY to save vertical content to an earlier vertical version. Mechanical 2015 objects cannot be converted to Mechanical 2012 objects; Civil3D 2017 objects cannot be converted to Civil3D 2012 objects; Plant3D 2016 objects cannot be converted to Plant3D 2014 objects. Even if the DWG file version is changed to an earlier version, the content version of vertical objects stays the same. Otherwise there would be no complaints about backwards version compatibility for the vertical products.
You obviously aren't reading the thread, and you cite as your only proof, user complaints about backwards version compatibility.
What is the AMSAVEASACADMXXXX family of commands for?
The OP has contradicted your statements by saving down to AutoCAD Mechanical 2014 format without any problem whatsoever.
And, perhaps you can explain what all of the entries on the drop-down list in this old screen shot are for, if not for doing what you claim can't be done:
@Activist_Investor wrote:
What is the AMSAVEASACADMXXXX family of commands for?
The OP has contradicted your statements by saving down to AutoCAD Mechanical 2014 format without any problem whatsoever.
The same thought indeed I had, when I read through the possibilities to export a drawing to other formats/versions.
At some point the incompatibility may be not downgradeable - that I do see and agree - but in the most simple case the shown "manual" SaveaS or the Command-SaveAs provide the functionallity to save a DWG to lower version.
However, I think it could be a nice feature to know how to do it via saveAs API (.NET or COM API).
Although the Enumeration(s) of both saveAs API`s (.NET-saveAs and COM-saveAs) suggests that an export to e.g. AM2014 should be possible, it failes.
Failes in terms of export/saveAs is succeeded, but when re-opened in other AutoCAD Session again the dialogue boxes appear demanding a recover of the drawing freshly saved drawing.
Perhaps I am doing a mistake here, and hoped to get a clue how to get it working via API (not Command) within this thread.
For the moment I can handle the demand by using the commandline and save the drawing in other (earlier) formats.
Thanks so far.
@dgorsman wrote:There is no way to save down vertical content, API or otherwise, that actually converts vertical objects to an earlier version. The one caveat that I know of, is a *very* brief interval where several versions of Civil3D could cross-communicate for common objects.
Out of curiosity, what does it report that it's actually fixing in the DWG file?
Hi dgorsman,
sorry I overread you question/post.
I`d like to cover you with required info for this.
So for sake of constructive investigation:
When I open such an "corrupt" drawing that needs recovery (exported via .NET), after I clicked on recover following info is displayed in CMD:
Loading Modeler DLLs.
Scanning completed.
Validating objects in the handle table.
Valid objects 3244 Invalid objects 0
Validating objects completed. 16 error opening *Model_Space's layout.
Setting layout id to null.
16 error opening *Paper_Space's layout.
Setting layout id to null.
Salvaged database from drawing.
Reading handle 118 object type AcAmProject
Error 67 (eDwgObjectImproperlyRead) Object discarded
Auditing Header
Auditing Tables
Auditing Entities Pass 1
Pass 1 3000 objects audited
Auditing Entities Pass 2
Duplicate name "ACAD_DSTYLE_DIMARC_LENGTH_SYMBOL" in Registered application symbol table.
Changed to "AUDIT_D_171012142427-0".
Pass 2 3000 objects audited
Auditing Blocks
22 Blocks audited
Auditing AcDsRecords
Total errors found 4 fixed 4
Erased 1 objects
Opening a Release 14 format file.
Substituting [simplex.shx] for [medtext].
Regenerating layout.
Regenerating model.
