1*46696af2SBarry Smith# Selecting Parts of Meshes (DMLabel) 2*46696af2SBarry Smith 3*46696af2SBarry SmithThe `DMLABEL` object is used to mark pieces of a mesh or `DM`, for example to indicate that a boundary condition should hold on that section. 4*46696af2SBarry SmithMarkers are integers, so it can be seen as a multimap between integers and mesh pieces. 5*46696af2SBarry Smith 6*46696af2SBarry SmithInsertion is amortized $O(1)$ since hash tables are used, 7*46696af2SBarry Smithbut each bin is then sorted so that extraction into sorted levels is also $O(1)$. The total cost should be $O(N log N)$ for $N$ entries. 8