Streams represent the flow of bulk material (as bulk streams, see Bulk Streams) or discrete entities (as discrete streams, see Discrete Streams) from one unit procedure to the next. Streams can be direct process inputs, intermediates or outputs (see Types of Streams). All attributes of input streams (composition, temperature, pressure, etc.) must be initialized by the user (see also Auto-Initialization of Input Streams) whereas the main attributes of intermediate and output streams are calculated by the application after the mass & energy (M&E) balances are executed. Streams are displayed on the process flowsheet as polylines made up strictly of horizontal and/or vertical segments. When drawing a stream, always start from the source and finish with the destination (see Classification of Input and Output Streams). After each stream is drawn, it is assigned a name that is generated using a automatically by the application using a prefix (like “S-”) and a number (see Automatic Procedure Name Generation). The chosen name is displayed on a name tag (see Stream Tags). The name tag is automatically positioned by the application (but can be adjusted by the user, if need be) and moves automatically when the stream’s shape changes. The auto-generated name can be changed by the user after the stream is created. A string can be given any name so long as it is unique among all stream names in the process. The appearance of streams (line color, thickness, location of name tag, etc.) is all kept by a stream style object (see Stream Style). The default stream style for bulk and discrete streams is kept by the process file and can be changed by the user (see Default Style for Process Elements). Also, individual streams can have their style modified if so desired through the Stream Style Dialog.