| Parameter Name | Description | Default(inch) |
| xo | x coordinate | 0 |
| yo | y coordinate | 0 |
| zo | z coordinate | 0 |
| sw | shaft width | 12 |
| sd | shaft depth | 12 |
| ph | pergola height | 180 |
| rh1 | shaft ratio to pergola height | 0.75 |
| s_nrow | number of shaft rows | 6 |
| s_gap_row | distance bet. shafts in rows | 120 |
| s_gap_col | distance bet. shafts in 2 columns | 120 |
| cw | width of capital lower_beam | 3 |
| ct | thickness of capital lower_beam | 12 |
| cwr | upper_beam width ratio to lower_beam | 1 |
| ctr | upper_beam thickness ratio to lower_beam | 1.5 |
| c_cant | cantilever length of upper_beam Perg_capital_frame | 6 |