How is the temperature displayed in a METAR/SPECI if it is unavailable?

In a METAR or SPECI report, when temperature information is not available, the entire group for temperature is omitted from the report. This is in line with the standard formatting of these reports, where data that cannot be accurately provided is simply left out rather than represented with placeholder codes or terms. Therefore, if the temperature cannot be ascertained, it will not be included in the report, indicating to the reader that the temperature information is not available at that time. This method allows for a clean and standardized reporting format, keeping the focus on available data while signaling that certain measurements were not collected.