The ClientBuildManagerParameter.PrecompilationFlags property determines how the assembly will be built. For example, you can set ClientBuildManagerParameter.PrecompilationFlags to PrecompilationFlags.Clean to recompile any previously compiled components, or set it to PrecompilationFlags.OverwriteTarget to permit the resulting assembly to overwrite any components in the target directory. The System.Web.Compilation.PrecompilationFlags enumerator has a FlagsAttribute attribute that allows a bitwise combination of its member values. The ClientBuildManagerParameter.PrecompilationFlags property can contain more than one value from the System.Web.Compilation.PrecompilationFlags enumeration to specify a combination of precompilation behaviors.