Can you add steps to reproduce? I'm not sure how to save a double array as .mcsv.

Steps to reproduce:

1) "Add data" with the attached .csv file: load as DoubleArray
2) "Save data" this DoubleArray:

2.1) if you choose .mcsv, it is saved as "Measurement CSV"(according to the text in "Save data". Reading it back tries to read it as a Volume!!??

2.2) if you save as .txt, you only have the option to load as "Color" or other unrelated types, but not as DoubleArray.

My suspicion is that there's a missing Qt IO class for this data type that should be registered with a factory so that the double arryas can be saved and loaded properly...

In vtkMRMLDoubleArrayStorageNode::InitializeSupportedReadFileTypes and InitializeSupportedWriteFileTypes it lists .mcsv files as the default extension which is correct.

Trying it out in Slicer, the main problem seems to be reloading them, they're being saved in the right format (Measurement CSV (.mcsv) is correct, a ruler appears in the save dialog with the description Annotation list CSV (.acsv)).

This isn't an Annotations module bug, it's a bug in the QT IO for loading, in Modules/Loadable/DoubleArrays/qSlicerDoubleArraysIO (look into: does the description have to match the storage node, will just fixing the extensions there do it (only lists .csv)), or in the load data dialogue box.

Yes, this fixes it:

Index: qSlicerDoubleArraysIO.cxx

--- qSlicerDoubleArraysIO.cxx (revision 22390)
+++ qSlicerDoubleArraysIO.cxx (working copy)
@@ -91,7 +91,7 @@
QStringList qSlicerDoubleArraysIO::extensions()const
{
return QStringList()

• << "Double Array (*.csv)"
• << "Double Array (*.mcsv)"
  ;
  }

Once the release releasing is done, I'll commit the change to the trunk and port it to the branch for the 4.3.1 release.

Fixed in svn 22396.
http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&amp;revision=22396

Minor regression is that .csv files can no longer be loaded as DoubleArray, .mcsv should be used instead. Perhaps this should be noted in the corresponding documentation.