A gipsy format srif file is a one column ascii text file containing n*(n+3)/2 elements of the upper triangle SRIF R matrix in column vector order (including n right-hand side terms) with additional n lines of the n parameter names attached. Thus, for n parameters the srif file has n*(n+5)/2 lines in total. The first n*(n+3)/2 lines are values, and the last n lines are names. For example, for a parameter vector of 3 parameters P1, P2, and P3, its srif file has the following 12 lines:
r11
r12
r22
r13
r23
r33
y1
y2
y3
"P1"
"P2"
"P3"
to represet the Square Root Information Factorization of normal equation:
r11*P1 + r12*P2 + r13*P3 = y1
         r22*P2 + r23*P3 = y2
                  r33*P3 = y3

All values are with respect to nominal parameter values that are used to linearize the observation equations. Nonminal values, if non-zero, need to be added back to solution. In a 4-column EST file, each line has the parameter name, estimate value, formal sigma and nominal value for one parameter.