What type of knot method is constrained in use on raising systems?

The dog and tails knot is often constrained in use on raising systems due to its specific function and design. This knot is primarily used for securing the ends of two ropes together, rather than for applications where load distribution and security during lifting are critical.

In raising systems, it's essential to have knots that can handle dynamic loads and provide predictable performance under tension. The dog and tails knot does not provide the same level of security and reliability when used for lifting as other knots might. Additionally, it can be more challenging to untie after being loaded, which can pose issues in rescue scenarios where quick de-rigging is necessary.

In contrast, knots like the figure-eight knot and bowline are well-suited for such applications because they maintain their integrity and are easier to untie after being loaded. The double fisherman’s knot is also effective for joining lines, but it is mostly used in the context of creating a secure connection between two ropes rather than being utilized in a raising system.