The midline is a term used in the layout of positions. Different markets (futures/stocks/foreign exchange, etc.). Moreover, different personal operation styles have different definitions of time, and there is no certain law;

For some operators, a month may be a long line, a week or so may be a middle line, and a day may be a short line or ultra-short line (15 minutes);

For some operators, a week may be short-term, a month or a quarter may be the middle line, and half a year or a year may be long-term.

However, the market generally believes that the daily line is short-term (the cycle is generally 3-5 days), the weekly line looks at the middle line, and the monthly line and above look at the long line.

You can Baidu the midline content.