The block valves or sectionalizing valves are a very important part of any pipeline. They are typically the main use. The most most frequent use is to isolate sections of a pipeline during normal operation when maintenance is required, so the pipeline can be emptied, maintained, or repaired if that's necessary.
The best environmental protection is to keep hydrocarbons in the pipe, so the NEB has a very extensive and rigorous prevention regulatory regime, including technical oversight and inspections, audits of management systems, and various kinds of escalating enforcement that's available. That's a huge focus for us, because pipelines need to be built, operated, and maintained in a way that prevents leaks or any kinds of ruptures like that.
The design and placement of block valves is complicated. They're large. They have downsides as well as upsides. In terms of increasing the complexity of the operating system, they may impose—because they're machines—mechanics in the middle of what would normally be a welded piece of pipe. It increases some complexity and stresses, etc. We require—