qa: unify unix epoch time descriptions

to "UNIX epoch time".

Call sites updated:
```
mocktime
getblockheader
getblock
pruneblockchain
getchaintxstats
getblocktemplate
setmocktime
getpeerinfo
setban
getnodeaddresses
getrawtransaction
importmulti
listtransactions
listsinceblock
gettransaction
getwalletinfo
getaddressinfo
```

10 files changed, 31 insertions, 23 deletions

diff --git a/src/init.cpp b/src/init.cpp
index e7dda59590..fe1a65b5e1 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -497,7 +497,7 @@ void SetupServerArgs()
     gArgs.AddArg("-logtimestamps", strprintf("Prepend debug output with timestamp (default: %u)", DEFAULT_LOGTIMESTAMPS), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logthreadnames", strprintf("Prepend debug output with name of the originating thread (only available on platforms supporting thread_local) (default: %u)", DEFAULT_LOGTHREADNAMES), ArgsManager::ALLOW_ANY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-logtimemicros", strprintf("Add microsecond precision to debug timestamps (default: %u)", DEFAULT_LOGTIMEMICROS), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
-    gArgs.AddArg("-mocktime=<n>", "Replace actual time with <n> seconds since epoch (default: 0)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
+    gArgs.AddArg("-mocktime=<n>", "Replace actual time with " + UNIX_EPOCH_TIME + " (default: 0)", ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-maxsigcachesize=<n>", strprintf("Limit sum of signature cache and script execution cache sizes to <n> MiB (default: %u)", DEFAULT_MAX_SIG_CACHE_SIZE), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-maxtipage=<n>", strprintf("Maximum tip age in seconds to consider node in initial block download (default: %u)", DEFAULT_MAX_TIP_AGE), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
     gArgs.AddArg("-printpriority", strprintf("Log transaction fee per kB when mining blocks (default: %u)", DEFAULT_PRINTPRIORITY), ArgsManager::ALLOW_ANY | ArgsManager::DEBUG_ONLY, OptionsCategory::DEBUG_TEST);
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 946152d9aa..6f97ab8bd1 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -742,8 +742,8 @@ static UniValue getblockheader(const JSONRPCRequest& request)
             "  \"version\" : n,         (numeric) The block version\n"
             "  \"versionHex\" : \"00000000\", (string) The block version formatted in hexadecimal\n"
             "  \"merkleroot\" : \"xxxx\", (string) The merkle root\n"
-            "  \"time\" : ttt,          (numeric) The block time in seconds since epoch (Jan 1 1970 GMT)\n"
-            "  \"mediantime\" : ttt,    (numeric) The median block time in seconds since epoch (Jan 1 1970 GMT)\n"
+            "  \"time\" : ttt,          (numeric) The block time expressed in " + UNIX_EPOCH_TIME + "\n"
+            "  \"mediantime\" : ttt,    (numeric) The median block time expressed in " + UNIX_EPOCH_TIME + "\n"
             "  \"nonce\" : n,           (numeric) The nonce\n"
             "  \"bits\" : \"1d00ffff\", (string) The bits\n"
             "  \"difficulty\" : x.xxx,  (numeric) The difficulty\n"
@@ -854,8 +854,8 @@ static UniValue getblock(const JSONRPCRequest& request)
             "     \"transactionid\"     (string) The transaction id\n"
             "     ,...\n"
             "  ],\n"
-            "  \"time\" : ttt,          (numeric) The block time in seconds since epoch (Jan 1 1970 GMT)\n"
-            "  \"mediantime\" : ttt,    (numeric) The median block time in seconds since epoch (Jan 1 1970 GMT)\n"
+            "  \"time\" : ttt,          (numeric) The block time expressed in " + UNIX_EPOCH_TIME + "\n"
+            "  \"mediantime\" : ttt,    (numeric) The median block time expressed in " + UNIX_EPOCH_TIME + "\n"
             "  \"nonce\" : n,           (numeric) The nonce\n"
             "  \"bits\" : \"1d00ffff\", (string) The bits\n"
             "  \"difficulty\" : x.xxx,  (numeric) The difficulty\n"
@@ -921,7 +921,7 @@ static UniValue pruneblockchain(const JSONRPCRequest& request)
 {
             RPCHelpMan{"pruneblockchain", "",
                 {
-                    {"height", RPCArg::Type::NUM, RPCArg::Optional::NO, "The block height to prune up to. May be set to a discrete height, or a unix timestamp\n"
+                    {"height", RPCArg::Type::NUM, RPCArg::Optional::NO, "The block height to prune up to. May be set to a discrete height, or to a " + UNIX_EPOCH_TIME + "\n"
             "                  to prune blocks whose block time is at least 2 hours older than the provided timestamp."},
                 },
                 RPCResult{
@@ -1573,7 +1573,7 @@ static UniValue getchaintxstats(const JSONRPCRequest& request)
                 },
                 RPCResult{
             "{\n"
-            "  \"time\": xxxxx,                         (numeric) The timestamp for the final block in the window in UNIX format.\n"
+            "  \"time\": xxxxx,                         (numeric) The timestamp for the final block in the window, expressed in " + UNIX_EPOCH_TIME + ".\n"
             "  \"txcount\": xxxxx,                      (numeric) The total number of transactions in the chain up to that point.\n"
             "  \"window_final_block_hash\": \"...\",      (string) The hash of the final block in the window.\n"
             "  \"window_final_block_height\": xxxxx,    (numeric) The height of the final block in the window.\n"
diff --git a/src/rpc/mining.cpp b/src/rpc/mining.cpp
index 85f9f1e8b7..fc16a31423 100644
--- a/src/rpc/mining.cpp
+++ b/src/rpc/mining.cpp
@@ -379,7 +379,7 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
             "  \"coinbasevalue\" : n,              (numeric) maximum allowable input to coinbase transaction, including the generation award and transaction fees (in satoshis)\n"
             "  \"coinbasetxn\" : { ... },          (json object) information for coinbase transaction\n"
             "  \"target\" : \"xxxx\",                (string) The hash target\n"
-            "  \"mintime\" : xxx,                  (numeric) The minimum timestamp appropriate for next block time in seconds since epoch (Jan 1 1970 GMT)\n"
+            "  \"mintime\" : xxx,                  (numeric) The minimum timestamp appropriate for the next block time, expressed in " + UNIX_EPOCH_TIME + "\n"
             "  \"mutable\" : [                     (array of string) list of ways the block template may be changed \n"
             "     \"value\"                          (string) A way the block template may be changed, e.g. 'time', 'transactions', 'prevblock'\n"
             "     ,...\n"
@@ -388,7 +388,7 @@ static UniValue getblocktemplate(const JSONRPCRequest& request)
             "  \"sigoplimit\" : n,                 (numeric) limit of sigops in blocks\n"
             "  \"sizelimit\" : n,                  (numeric) limit of block size\n"
             "  \"weightlimit\" : n,                (numeric) limit of block weight\n"
-            "  \"curtime\" : ttt,                  (numeric) current timestamp in seconds since epoch (Jan 1 1970 GMT)\n"
+            "  \"curtime\" : ttt,                  (numeric) current timestamp in " + UNIX_EPOCH_TIME + "\n"
             "  \"bits\" : \"xxxxxxxx\",              (string) compressed target of next block\n"
             "  \"height\" : n                      (numeric) The height of the next block\n"
             "}\n"
diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index d73dd6e52d..d967d2bcca 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -343,7 +343,7 @@ static UniValue setmocktime(const JSONRPCRequest& request)
             RPCHelpMan{"setmocktime",
                 "\nSet the local time to given timestamp (-regtest only)\n",
                 {
-                    {"timestamp", RPCArg::Type::NUM, RPCArg::Optional::NO, "Unix seconds-since-epoch timestamp\n"
+                    {"timestamp", RPCArg::Type::NUM, RPCArg::Optional::NO, UNIX_EPOCH_TIME + "\n"
             "   Pass 0 to go back to using the system time."},
                 },
                 RPCResults{},
diff --git a/src/rpc/net.cpp b/src/rpc/net.cpp
index f1dcc9b607..6ee91f139d 100644
--- a/src/rpc/net.cpp
+++ b/src/rpc/net.cpp
@@ -89,11 +89,11 @@ static UniValue getpeerinfo(const JSONRPCRequest& request)
             "         ...\n"
             "     ],\n"
             "    \"relaytxes\":true|false,    (boolean) Whether peer has asked us to relay transactions to it\n"
-            "    \"lastsend\": ttt,           (numeric) The time in seconds since epoch (Jan 1 1970 GMT) of the last send\n"
-            "    \"lastrecv\": ttt,           (numeric) The time in seconds since epoch (Jan 1 1970 GMT) of the last receive\n"
+            "    \"lastsend\": ttt,           (numeric) The " + UNIX_EPOCH_TIME + " of the last send\n"
+            "    \"lastrecv\": ttt,           (numeric) The " + UNIX_EPOCH_TIME + " of the last receive\n"
             "    \"bytessent\": n,            (numeric) The total bytes sent\n"
             "    \"bytesrecv\": n,            (numeric) The total bytes received\n"
-            "    \"conntime\": ttt,           (numeric) The connection time in seconds since epoch (Jan 1 1970 GMT)\n"
+            "    \"conntime\": ttt,           (numeric) The " + UNIX_EPOCH_TIME + " of the connection\n"
             "    \"timeoffset\": ttt,         (numeric) The time offset in seconds\n"
             "    \"pingtime\": n,             (numeric) ping time (if available)\n"
             "    \"minping\": n,              (numeric) minimum observed ping time (if any at all)\n"
@@ -534,7 +534,7 @@ static UniValue setban(const JSONRPCRequest& request)
                     {"subnet", RPCArg::Type::STR, RPCArg::Optional::NO, "The IP/Subnet (see getpeerinfo for nodes IP) with an optional netmask (default is /32 = single IP)"},
                     {"command", RPCArg::Type::STR, RPCArg::Optional::NO, "'add' to add an IP/Subnet to the list, 'remove' to remove an IP/Subnet from the list"},
                     {"bantime", RPCArg::Type::NUM, /* default */ "0", "time in seconds how long (or until when if [absolute] is set) the IP is banned (0 or empty means using the default time of 24h which can also be overwritten by the -bantime startup argument)"},
-                    {"absolute", RPCArg::Type::BOOL, /* default */ "false", "If set, the bantime must be an absolute timestamp in seconds since epoch (Jan 1 1970 GMT)"},
+                    {"absolute", RPCArg::Type::BOOL, /* default */ "false", "If set, the bantime must be an absolute timestamp expressed in " + UNIX_EPOCH_TIME},
                 },
                 RPCResults{},
                 RPCExamples{
@@ -691,7 +691,7 @@ static UniValue getnodeaddresses(const JSONRPCRequest& request)
                 RPCResult{
             "[\n"
             "  {\n"
-            "    \"time\": ttt,                (numeric) Timestamp in seconds since epoch (Jan 1 1970 GMT) keeping track of when the node was last seen\n"
+            "    \"time\": ttt,                (numeric) The " + UNIX_EPOCH_TIME + " of when the node was last seen\n"
             "    \"services\": n,              (numeric) The services offered\n"
             "    \"address\": \"host\",          (string) The address of the node\n"
             "    \"port\": n                   (numeric) The port of the node\n"
diff --git a/src/rpc/rawtransaction.cpp b/src/rpc/rawtransaction.cpp
index 6f24caee21..f328f20c71 100644
--- a/src/rpc/rawtransaction.cpp
+++ b/src/rpc/rawtransaction.cpp
@@ -139,7 +139,7 @@ static UniValue getrawtransaction(const JSONRPCRequest& request)
             "  ],\n"
             "  \"blockhash\" : \"hash\",   (string) the block hash\n"
             "  \"confirmations\" : n,      (numeric) The confirmations\n"
-            "  \"blocktime\" : ttt         (numeric) The block time in seconds since epoch (Jan 1 1970 GMT)\n"
+            "  \"blocktime\" : ttt         (numeric) The block time expressed in " + UNIX_EPOCH_TIME + "\n"
             "  \"time\" : ttt,             (numeric) Same as \"blocktime\"\n"
             "}\n"
                     },
diff --git a/src/rpc/util.cpp b/src/rpc/util.cpp
index 0791a365fe..78586c22f9 100644
--- a/src/rpc/util.cpp
+++ b/src/rpc/util.cpp
@@ -13,6 +13,8 @@
 
 #include <tuple>
 
+const std::string UNIX_EPOCH_TIME = "UNIX epoch time";
+
 void RPCTypeCheck(const UniValue& params,
                   const std::list<UniValueType>& typesExpected,
                   bool fAllowNull)
diff --git a/src/rpc/util.h b/src/rpc/util.h
index 9304e1fefb..065a992a88 100644
--- a/src/rpc/util.h
+++ b/src/rpc/util.h
@@ -22,6 +22,12 @@
 
 #include <boost/variant.hpp>
 
+/**
+ * String used to describe UNIX epoch time in documentation, factored out to a
+ * constant for consistency.
+ */
+extern const std::string UNIX_EPOCH_TIME;
+
 class FillableSigningProvider;
 class CPubKey;
 class CScript;
diff --git a/src/wallet/rpcdump.cpp b/src/wallet/rpcdump.cpp
index d95481500d..633ac1b16d 100644
--- a/src/wallet/rpcdump.cpp
+++ b/src/wallet/rpcdump.cpp
@@ -1286,7 +1286,7 @@ UniValue importmulti(const JSONRPCRequest& mainRequest)
                                     {"scriptPubKey", RPCArg::Type::STR, RPCArg::Optional::NO, "Type of scriptPubKey (string for script, json for address). Should not be provided if using a descriptor",
                                         /* oneline_description */ "", {"\"<script>\" | { \"address\":\"<address>\" }", "string / json"}
                                     },
-                                    {"timestamp", RPCArg::Type::NUM, RPCArg::Optional::NO, "Creation time of the key in seconds since epoch (Jan 1 1970 GMT),\n"
+                                    {"timestamp", RPCArg::Type::NUM, RPCArg::Optional::NO, "Creation time of the key expressed in " + UNIX_EPOCH_TIME + ",\n"
         "                                                              or the string \"now\" to substitute the current synced blockchain time. The timestamp of the oldest\n"
         "                                                              key will determine how far back blockchain rescans need to begin for missing wallet transactions.\n"
         "                                                              \"now\" can be specified to bypass scanning, for keys which are known to never have been used, and\n"
diff --git a/src/wallet/rpcwallet.cpp b/src/wallet/rpcwallet.cpp
index d906f6ddf0..63cbe02b17 100644
--- a/src/wallet/rpcwallet.cpp
+++ b/src/wallet/rpcwallet.cpp
@@ -1374,14 +1374,14 @@ static const std::string TransactionDescriptionString()
            "    \"blockhash\": \"hashvalue\",                  (string) The block hash containing the transaction.\n"
            "    \"blockheight\": n,                          (numeric) The block height containing the transaction.\n"
            "    \"blockindex\": n,                           (numeric) The index of the transaction in the block that includes it.\n"
-           "    \"blocktime\": xxx,                          (numeric) The block time in seconds since epoch (1 Jan 1970 GMT).\n"
+           "    \"blocktime\": xxx,                          (numeric) The block time expressed in " + UNIX_EPOCH_TIME + ".\n"
            "    \"txid\": \"transactionid\",                   (string) The transaction id.\n"
            "    \"walletconflicts\": [                       (array) Conflicting transaction ids.\n"
            "      \"txid\",                                  (string) The transaction id.\n"
            "      ...\n"
            "    ],\n"
-           "    \"time\": xxx,                               (numeric) The transaction time in seconds since epoch (midnight Jan 1 1970 GMT).\n"
-           "    \"timereceived\": xxx,                       (numeric) The time received in seconds since epoch (midnight Jan 1 1970 GMT).\n"
+           "    \"time\": xxx,                               (numeric) The transaction time expressed in " + UNIX_EPOCH_TIME + ".\n"
+           "    \"timereceived\": xxx,                       (numeric) The time received expressed in " + UNIX_EPOCH_TIME + ".\n"
            "    \"comment\": \"...\",                          (string) If a comment is associated with the transaction, only present if not empty.\n"
            "    \"bip125-replaceable\": \"yes|no|unknown\",    (string) Whether this transaction could be replaced due to BIP125 (replace-by-fee);\n"
            "                                                     may be unknown for unconfirmed transactions not in the mempool\n";
@@ -2428,10 +2428,10 @@ static UniValue getwalletinfo(const JSONRPCRequest& request)
             "  \"unconfirmed_balance\": xxx,        (numeric) DEPRECATED. Identical to getbalances().mine.untrusted_pending\n"
             "  \"immature_balance\": xxxxxx,        (numeric) DEPRECATED. Identical to getbalances().mine.immature\n"
             "  \"txcount\": xxxxxxx,                (numeric) the total number of transactions in the wallet\n"
-            "  \"keypoololdest\": xxxxxx,           (numeric) the timestamp (seconds since Unix epoch) of the oldest pre-generated key in the key pool\n"
+            "  \"keypoololdest\": xxxxxx,           (numeric) the " + UNIX_EPOCH_TIME + " of the oldest pre-generated key in the key pool\n"
             "  \"keypoolsize\": xxxx,               (numeric) how many new keys are pre-generated (only counts external keys)\n"
             "  \"keypoolsize_hd_internal\": xxxx,   (numeric) how many new keys are pre-generated for internal use (used for change outputs, only appears if the wallet is using this feature, otherwise external keys are used)\n"
-            "  \"unlocked_until\": ttt,             (numeric) the timestamp in seconds since epoch (midnight Jan 1 1970 GMT) that the wallet is unlocked for transfers, or 0 if the wallet is locked\n"
+            "  \"unlocked_until\": ttt,             (numeric) the " + UNIX_EPOCH_TIME + " until which the wallet is unlocked for transfers, or 0 if the wallet is locked\n"
             "  \"paytxfee\": x.xxxx,                (numeric) the transaction fee configuration, set in " + CURRENCY_UNIT + "/kB\n"
             "  \"hdseedid\": \"<hash160>\"            (string, optional) the Hash160 of the HD seed (only present when HD is enabled)\n"
             "  \"private_keys_enabled\": true|false (boolean) false if privatekeys are disabled for this wallet (enforced watch-only wallet)\n"
@@ -3743,7 +3743,7 @@ UniValue getaddressinfo(const JSONRPCRequest& request)
             "                                                         hdseedid) and relation to the wallet (ismine, iswatchonly).\n"
             "  \"iscompressed\" : true|false,        (boolean, optional) If the pubkey is compressed.\n"
             "  \"label\" :  \"label\"                  (string) The label associated with the address. Defaults to \"\". Equivalent to the name field in the labels array.\n"
-            "  \"timestamp\" : timestamp,            (number, optional) The creation time of the key if available, expressed in seconds since Epoch Time (Jan 1 1970 GMT).\n"
+            "  \"timestamp\" : timestamp,            (number, optional) The creation time of the key, if available, expressed in " + UNIX_EPOCH_TIME + ".\n"
             "  \"hdkeypath\" : \"keypath\"             (string, optional) The HD keypath, if the key is HD and available.\n"
             "  \"hdseedid\" : \"<hash160>\"            (string, optional) The Hash160 of the HD seed.\n"
             "  \"hdmasterfingerprint\" : \"<hash160>\" (string, optional) The fingerprint of the master key.\n"