Volume is the total amount of assets traded in a specific period of time. The 24-hour Volume indicator is used to measure the total volume of a symbol traded in the last 24 hours, expressed as in currency. It can be used to measure the market's interest in a particular symbol.
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You can read the full documentation and explanation of how it works on the original indicator's page.
This indicator uses the code from the original indicator. Instead of a histogram, it displays the value as text. If the symbol has low 24-hour volume, the text changes color to provide a warning.