HP Prime Graphing Wireless Calculator - Manual (Page 236)

232 Variables
serrLine Contains the standard error of the line for the linear t-test.
serrSlope Contains the standard error of the slope for either the
linear t-test or the confidence interval for slope.
serrY Contains the standard error of ŷ for either the confidence
interval for a mean response or the prediction interval for
a future response.
Slope Contains the value of the slope of the regression line for
either the linear t-test or the confidence interval for slope.
TestScore Contains the Z- or t-distribution value calculated from the
hypothesis test or confidence interval inputs.
TestValue Contains the value of the experimental variable
associated with the TestScore.
Yval Contains the value of ŷ for either the confidence interval
for a mean response or the prediction interval for a future
response.