Merge cells in table columns

[BerSie]

Create an opportunity to define columns in a table where the cells are merged if the adjacent values are the same (in html rowSpan would be used). I decided to go as a starting point with an HTML5 collection of propertyPath that can be applied to UI.LineItem. Imo this new annotation makes only sense for UI.LineItem, and I didn't want to change the term itself.
Other possibilities would be applying the annotation to properties or adding something to the UI.PresentationVariant.

[HeikoTheissen]

You annotate a UI.LineItem with a collection of Edm.PropertyPaths. But the line item contains

<Record Type="UI.DataField">
  <PropertyValue Property="Value" Path="..." />
</Record>

and can even combine more than one property.

I suggest to annotate the UI.DataField record instead with a Boolean term:

<Record Type="UI.DataField">
  <Annotation Term="HTML5.PreferRowSpan" Bool="true" />
  <PropertyValue Property="Value" Path="..." />
</Record>

[BerSie]

I suggest to annotate the UI.DataField record instead with a Boolean term:

<Record Type="UI.DataField">
  <Annotation Term="HTML5.PreferRowSpan" Bool="true" />

That sounds indeed interesting - thank you @HeikoTheissen ! The only thing that I'm not 100% convinced of is the name (esp. the "Prefer"). I will prepare a new commit.

[HeikoTheissen]

Add reference to UI vocabulary.

[ralfhandl]

I like the new term name and where it applies!