In Linear Leios, RB headers announce EBs. Therefore, if an adversary wants to issue equivocating EBs (eg to waste valuable bandwidth), they'll have to issue equivocating RBs headers.

The Linear Leios node does not diffuse equivocating EBs nor vote for them. To do so, the node must detect equivocation, and moreover do so before it's "too late" (ie within 3∆_hdr). For that reason, we need to diffuse RB headers more broadly than their RB bodies (since eg tiebreakers might prevent an RB header from diffusing to all nodes) and also more quickly than their RB bodies (since---even with RB Diffusion Pipelining---an RB header is only allowed to be one hop ahead of its RB body.)

Thus, Linear Leios involves a dedicated mini protocol that diffuses only valid RB headers.

However, opcert issue numbers mean that an RB header cannot be fully validated in the absence of its preceding headers. Those generally should have arrived at the node, but there's no guarantee---especially if they were equivocated!

This Issue is to figure out how this mini protocol should work, for the specific goal of detecting (and proving) equivocation of Praos elections. I'm suspecting "full" validation might not be necessary.