[book]
title = "extension_compatibility"

[preprocessor.my-preprocessor]
command = "./my-preprocessor"
custom-config = true
optional = true
[preprocessor.my-preprocessor.custom-table]
extra = "abc"

[output.html]

[output.my-renderer]
command = "./my-renderer"
custom-config = "renderer settings"
optional = true
[output.my-renderer.custom-table]
extra = "xyz"