You may create, use, and choose to hide or display several annotation layers in order to separate different kinds of annotations, have different versions of the same Piece, work collaboratively, etc. 

For example, you could use a layer for bowings and another layer for personal markings.

Common actions

The following actions are found in the Layers panel:

• Create a layer: click on the + button
• Select a layer in order to annotate it : click on it in the list. It will appear bold and highlighted in the list, and all annotations you will make from that moment and until you select another layer will be saved on this layer. The name of the current active layer is displayed next to the layers icon in the annotation toolbar.
• Hide/Show a layer: Tap the eye icon next to the name of a Layer to hide or show it
• Delete a layer: swipe left on the row.
• Duplicate a layer: swipe left on the row.
• Edit a layer's title: click on the “Edit” button and edit the title text field
• Copy/Paste a layer: click on the “Edit” button, select the layer(s) you want to copy to the clipboard, and tap on the "Copy" button. You can then open another piece and paste the copied layer(s) by opening its layer panel, click on the “Edit” button, and tap on the "Paste" button

Privacy settings

When a piece is enclosed in a collaborative Project, you can use annotation layers to organize your annotations, quickly hide or show them, make them available or not to other project members, etc.

Read this article to know more about this.