The Background

All fixed, non-editable objects must be on the same layer, the Background Layer.

To specify the layer as the Background Layer, add a hyphen prefix (-) to the layer name e.g. –Background
The Background Layer should be kept as the lowest stacking layer within the Layer Palette, so that objects on the Background Layer do not obstruct any editable objects (elements below the -Background layer, will be deleted);
Paragraph Styles must be created for all fonts used on the Background Layer. If you do not want the font to appear as an option for an Editable Text object, then the text should be converted to outlines and no Paragraph Style is necessary for those elements.

Don't lock the -Background Layer

Some files from older versions of InDesign® can fail to build when the -Background layer is locked.

You can use most features and effects within InDesign® on the Background Layer that adhere to Designing for Production e.g. gradients, vectors, drop shadows, tints etc. The only features not supported are open paths (all vector shapes must be closed paths with no stray bezier nodes) and Text Wrap as this can affect Editable Objects within the template . Ensure you do not use any of the Text Wrap options, other than the default.

Final Check:
Items not supported on the -Background Layer

Text Wrap feature;
Open paths on vector shapes;
Fonts NOT from the Template Font List in Flyerlink®. Fonts not in this list must be converted to outlines or used within a rasterised image.