diff --git a/spec_files/README.md b/spec_files/README.md
index 719abbd..372d38a 100644
--- a/spec_files/README.md
+++ b/spec_files/README.md
@@ -6,21 +6,33 @@
 
 ## ARTEMIS 3 .SPEC FILES
 
-Artemis 3 .spec files are used by the package **pyinstaller** (https://www.pyinstaller.org/) to build a single standalone executable. The extreme versatility of this package is the fact that every external dependency is already embedded into the bundle. The interpreter of Python 3 is also included.
+Artemis 3 .spec files are used by the package **pyinstaller** (https://www.pyinstaller.org/) to build a single standalone executable (or a one-dir package). The extreme versatility of this package is the fact that every external dependency is already embedded into the bundle. The interpreter of Python 3 is also included.
 
 ## Requirements
 - Python 3.7.0+
 - Pyinstaller
+- 
+**IMPORTANT:** *To generate the standalone and the one-dir package, you must use an operating system that coincides with the target one (pyinstaller doesn't allow cross-compilation).* 
 
-## Package Building
-**IMPORTANT:** *To generate the standalone, you must use an operating system that coincides with the target one (pyinstaller doesn't allow cross-compilation).* 
+## Package Building (standalone aka one-file, high portability, **suggested**)
 1. Download a fresh copy of the git repository.
-2. Choose the target OS in `spec_files` folder and copy the whole content into `src`
+2. Choose the target OS in `spec_files` folder and copy the whole content (except the Artemis_onedir.spec file) into `src`
 3. Open a terminal into `src` and run:
 ```
 pyinstaller Artemis.spec
 ```
-4. The ready-to-use compiled software is now present into `src/dist` folder.
+4. Copy the `src/theme` folder into `src/dist`.
+5. The ready-to-use compiled software is now present into `src/dist` folder.
+
+## Package Building (one-dir, shorter startup time, low portability)
+1. Download a fresh copy of the git repository.
+2. Choose the target OS in `spec_files` folder and copy the whole content (except the Artemis.spec file) into `src`
+3. Open a terminal into `src` and run:
+```
+pyinstaller Artemis_onedir.spec
+```
+4. Copy the `src/theme` folder into `src/dist/Artemis`.
+5. The ready-to-use compiled software is now present into `src/dist` folder as a bundle. All the libraries are clearly present.
 
 ## License
 This program (ARTEMIS 3, 2014-2019) is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.