+4. Locating packages
+
+Most packages are not self-contained, but depend on other packages. When such
+dependencies are encountered, the packages need to be located. This section
+describes the various places Builder looks for them from.
+
+First, Builder asks pkg-config if it knows the location of the source
+directory of the package. This is stored in the source variable in the .pc
+file, and is automatically put there by Builder. If the variable is found,
+Builder further verifies that it refers to an existing directory which
+contains a Build file, so that removed sources do not cause undue failures.
+
+If pkg-config does not know about the source, Builder consults its own package
+path. Currently this is hardcoded to contain the main package's source
+directory and its parent directory. To be found this way, the directory
+should be named the same as the package, optionally followed by a dash and a
+version number (or really anything; the part after the last dash is ignored).
+
+If the source can't be found at all, Builder will then turn to using a binary
+package. Builder's native packages are considered first. They are normally
+stored in <prefix>/share/builder with the extension bpk. The base part of the
+filename should be the as the package's name.
+
+Finally, pkg-config is consulted for the build flags of the package in the
+normal way. The flags need to be translated to Builder's internal
+representation, so if the package requires very unusual flags, it may not
+work.
+
+A package that can't be found after all these steps might as well not exist.
+
+-------------------------------------------------------------------------------
+
+5. Command line options