think in targets

00_targets/README.md

-# Define Targets
+# Think in targets!
+
+This recipe illustrates how to build a basic application. 
+It consists of a backend library and an application frontend.
+
+## Define the target type
 [add_library]([https://cmake.org/cmake/help/latest/command/add_library.html])  
 [add_executable]([https://cmake.org/cmake/help/latest/command/add_executable.html])
 
-# Set Target Properties
-[target_compile_definitions]([https://cmake.org/cmake/help/latest/command/target_compile_definitions.html])  
-[target_compile_options]([https://cmake.org/cmake/help/latest/command/target_compile_options.html])  
-[target_include_directories]([https://cmake.org/cmake/help/latest/command/target_include_directories.html])  
-[target_link_libraries]([https://cmake.org/cmake/help/latest/command/target_link_libraries.html])  
-[target_link_options]([https://cmake.org/cmake/help/latest/command/target_link_options.html])  
-[target_sources]([https://cmake.org/cmake/help/latest/command/target_sources.html])
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+## Set target properties
+| Aim                                    | Command                                                                                                     |
+|----------------------------------------|-------------------------------------------------------------------------------------------------------------|
+| add definitions                        | [target_compile_definitions]([https://cmake.org/cmake/help/latest/command/target_compile_definitions.html]) | 
+| add compile flags                      | [target_compile_options]([https://cmake.org/cmake/help/latest/command/target_compile_options.html])         |
+| add include directories                | [target_include_directories]([https://cmake.org/cmake/help/latest/command/target_include_directories.html]) |
+| add a dependency, link against library | [target_link_libraries]([https://cmake.org/cmake/help/latest/command/target_link_libraries.html])           |
+| add linker options                     | [target_link_options]([https://cmake.org/cmake/help/latest/command/target_link_options.html])               |
+| add sources                            | [target_sources]([https://cmake.org/cmake/help/latest/command/target_sources.html])                         |
+
+## Usage requirements
+https://cmake.org/cmake/help/latest/manual/cmake-buildsystem.7.html#transitive-usage-requirements
+
+| keyword       | result                                                     |
+|---------------|------------------------------------------------------------|
+| **PRIVATE**   | only relevant for the target                               |
+| **INTERFACE** | only relevant for targets depending on this target         |
+| **PUBLIC**    | relevant for both, the target itself and dependent targets |
+
+## How to link against a "supported" third-party library?
+Find the library with [find_package]([https://cmake.org/cmake/help/latest/command/find_package.html]) and link against 
+the imported target with [target_link_libraries]([https://cmake.org/cmake/help/latest/command/target_link_libraries.html]).
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