But the bad thing is that the national standard version will generally be one or more versions later than the IEC version, so sometimes you can see the national standard and the British standard will not match, but generally speaking, it is not the same as the IEC version, but it is not a good idea. But the bad thing is that the national standard version is usually one or more versions later than the IEC version, so sometimes you can't see the difference between the national standard and the British standard, but it's more or less the same, so if you can't see the difference, you have to look at it in detail.