[#RPCArg-Fallback]
= xref:RPCArg.adoc[RPCArg]::Fallback
:relfileprefix: ../
:mrdocs:

The argument&apos;s default&colon; an optionality marker, a default hint, or a default value&period;

== Synopsis

Declared in `&lt;rpc&sol;util&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
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using Fallback = std::variant&lt;Optional, DefaultHint, Default&gt;;
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