diff --git a/README.md b/README.md
index ff0a56b..0fb3ef6 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,8 @@ cmake -DCMAKE_INSTALL_PREFIX=./FairLogger_install ../FairLogger
 cmake --build . --target install
 ```
 
+FairLogger bundles a version of the [fmt](https://github.com/fmtlib/fmt) library. You can override this with your own fmt installation via the `-DUSE_EXTERNAL_FMT=ON` and `-DFMT_ROOT=/fmt/location` CMake switches.
+
 ## Usage
 
 In your `CMakeLists.txt`:
@@ -35,6 +37,8 @@ find_package(FairLogger)
 
 `find_package(FairLogger)` will define an imported target `FairLogger::FairLogger`.
 
+In case of external fmt, the using project will need to find it.
+
 ## CMake options
 
 On command line:
@@ -49,7 +53,18 @@ On command line:
 
 All log calls go through the provided LOG(severity) macro. Output through this macro is thread-safe. Logging is done to cout, file output and/or custom sinks.
 
-## 2. Severity
+## 2. Additional macros
+
+A number of additional logging macros are provided:
+
+- `LOGV(severity, verbosity)` Log the line with the provided verbosity, e.g. `LOG(info, veryhigh) << "abcd";`
+- `LOGF(severity, ...)` The arguments are given to `fmt::format` and the result is logged, e.g. `LOGF(info, "Hello {}!", "world");`
+- `LOGP(severity, ...)` The arguments are given to `fmt::printf` and the result is logged, e.g. `LOGP(info, "Hello %s!", "world");`
+- `LOGN(severity)` Logs an empty line, e.g. `LOGN(info);`
+- `LOG_IF(severity, condition)` Logs the line if the provided condition if true
+- `LOGD(severity, file, line, f)` Logs the line with the provided file, line and function parameters (only if the active verbosity allows it).
+
+## 3. Severity
 
 The log severity is controlled via:
 ```C++
@@ -79,21 +94,25 @@ where severity level is one of the following:
 
 Logger will log the chosen severity and all above it (except "nolog", which deactivates logging for that sink completely). Fatal severity is always logged.
 
-## 3. Verbosity
+## 4. Verbosity
 
 The log verbosity is controlled via:
 ```C++
 fair::Logger::SetVerbosity("<verbosity level>");
 ```
 
-it is same for all sinks, and is one of the following values: `verylow`, `low`, `medium`, `high`, `veryhigh`, which translates to following output:
+it is same for all sinks, and is one of the following values: `verylow`, `low`, `medium`, `high`, `veryhigh`, `user1`, `user2`, `user3`, `user4`, which translates to following output:
 
 ```
 verylow:  message
 low:      [severity] message
 medium:   [HH:MM:SS][severity] message
-high:     [process name][HH:MM:SS:µS][severity] message
+high:     [process name][HH:MM:SS][severity] message
 veryhigh: [process name][HH:MM:SS:µS][severity][file:line:function] message
+user1:    [severity] message
+user2:    [severity] message
+user3:    [severity] message
+user4:    [severity] message
 ```
 
 When running a FairMQ device, the log severity can be simply provided via `--verbosity <level>` cmd option.
@@ -122,7 +141,7 @@ auto spec = fair::VerbositySpec::Make(VerbositySpec::Info::timestamp_s,
 | `fair::VerbositySpec::Info::file_line_function` | `[file:line:function]` |
 
 
-### 3.1 `BOOST_PRETTY_FUNCTION` support
+### 4.1 `BOOST_PRETTY_FUNCTION` support
 
 By default, the `veryhigh` verbosity prints the function name from which the `LOG` macro was invoked. If you desire a more verbose function signature including the full namespace, return value and function arguments, you can enable support for `BOOST_PRETTY_FUNCTION`
 
@@ -136,7 +155,7 @@ By default, the `veryhigh` verbosity prints the function name from which the `LO
 
 In the latter case, the user needs to take care of adding the boost include path to the compiler search path manually (e.g. `-I/path/to/boost/include`).
 
-## 4. Color
+## 5. Color
 
 Colored output on console can be activated with:
 ```C++
@@ -145,7 +164,7 @@ Logger::SetConsoleColor(true);
 
 When running a FairMQ device, the log color (console) can be simply provided via `--color <true/false>` cmd option (default is true).
 
-## 5. File output
+## 6. File output
 
 Output to file can be enabled via:
 ```C++
@@ -155,7 +174,7 @@ which will add output to "test_log" filename (if third parameter is `true` it wi
 
 When running a FairMQ device, the log file can be simply provided via `--log-to-file <filename_prefix>` cmd option (this will also turn off console output).
 
-## 5.5 Custom sinks
+## 7. Custom sinks
 
 Custom sinks can be added via `Logger::AddCustomSink("sink name", "<severity>", callback)` method.
 
diff --git a/logger/Logger.h b/logger/Logger.h
index 85935b1..ab80c04 100644
--- a/logger/Logger.h
+++ b/logger/Logger.h
@@ -79,7 +79,7 @@ enum class Severity : int
 // verylow:  message
 // low:      [severity] message
 // medium:   [HH:MM:SS][severity] message
-// high:     [process name][HH:MM:SS:µS][severity] message
+// high:     [process name][HH:MM:SS][severity] message
 // veryhigh: [process name][HH:MM:SS:µS][severity][file:line:function] message
 enum class Verbosity : int
 {