Read the YAML metadata (and any common _output.yml file) for the
document and return an output format object that can be
passed to the render function.
resolve_output_format(input, output_format = NULL, output_options = NULL,
encoding = getOption("encoding"))Input file (Rmd or plain markdown)
Name of output format (or NULL to use
the default format for the input file).
List of output options that should override the options specified in metadata.
The encoding of the input file; see file.
An R Markdown output format definition that can be passed to
render.
This function is useful for front-end tools that need to modify the default behavior of an output format.