The FT-7900 has 50 sets of PMS memory channels. This feature allows you to set sub-band limits for either scanning or manual VFO operation.
The system operates by have pairs of memories labelled L1 and U1 through L50 and U50. The Lnn memory defines the lower limit of the range, and the Unn memory defines the upper limit.
When you have an image loaded, click on the PMS tab to show the memories:
To add a new lower/upper pair, click in the lower frequency cell of the desired memory pair and enter the frequency. Now do the same for the upper frequency.
Now make any changes to the other settings in the memories.
When starting PMS mode, if you select the lower memory before pressing the BAND(SEL) button you will get the attributes of the Lnn memory applied. If you select the upper memory then the attributes of the Unn memory are applied instead. So you could, for example, have the lower frequency set for FM, and the upper set for FMN and so on.
To delete a PMS memory pair, right-click anywhere in the row of the pair to be deleted and choose the 'Delete PMS memory pair' command in the pop-up menu.