As far as I can understand, this structure qill be sent to the peer, but it uses a variable type which is typical of NSS. This might make it not compatible with other applications.

[FDeRubeis]

nss-tlsn/nss/lib/ssl/tlsproof.h

Lines 57 to 68 in 5730a7a

	#define PROOF_PAR_SIZE (sizeof(PRUint16) + sizeof(PRUint16) + sizeof(PRUint16) + sizeof(PRUint16) + sizeof(PRUint64) + sizeof(PRUint64) + sizeof(PRUint16) + sizeof(PRUint16) + sizeof(SSLHashType))
	typedef struct ProofParStr{
	PRUint16 hash_size;
	PRUint16 salt_size;
	PRUint16 chunk_size;
	PRUint16 num_proof_nodes;
	PRUint64 startTime;
	PRUint64 stopTime;
	PRUint16 sig_len; // Signature is directly after this struct
	PRUint16 cert_chain_len; // Certificate Chain is after the signature
	SSLHashType hash_type;
	} ProofPar;

[FDeRubeis]

nss-tlsn/nss/lib/ssl/tlsproof.c

Line 1615 in 5730a7a

proofPar.hash_type = tls13_GetHash(ss);