For software that interfaces with Bitcoin Core via RPC, it can be useful to know whether the fRelayTxes flag is set. It could be added to `getnetworkinfo`.

return error("%s: OpenBlockFile failed", __func__);
            CBlockHeader header;
            try {
                file >> header;
                fseek(file.Get(), postx.nTxOffset, SEEK_CUR);
                file >> txOut;
            } catch (const std::exception& e) {
                return error("%s: Deserialize or I/O error - %s", __func__, e.what());
            }
            hashBlock = header.GetHash();
            if (txOut.GetHash() != hash)
                return error("%s: txid mismatch", __func__);
            return true;
        }
    }
    if (fAllowSlow) { 
        int nHeight = -1;
        {
            const CCoinsViewCache& view = *pcoinsTip;
            const CCoins* coins = view.AccessCoins(hash);
            if (coins)
                nHeight = coins->nHeight;
        }
        if (nHeight > 0)
            pindexSlow = chainActive[nHeight];
    }
    if (pindexSlow) {
        CBlock block;
        if (ReadBlockFromDisk(block, pindexSlow, consensusParams)) {
            BOOST_FOREACH(const CTransaction &tx, block.vtx) {