Note that the height changes are not always negative.
While subsidence is downward forward through time,
the sense of the time change can be negative.

In most instances, the leveling occurred before the 
GPS observation and the height change was negative.
However, this is not the case for the following PID's: 

AU0451 BH1119 BH1094 BJ1527 AT1395 AU1291 AU0402 
AU2180 AU3323 AU1176 AT0760 BH1538 BH3007



     ORIGINAL               REVISED
--------------------   -----------------
 PID      NAVD 88       NAVD 88    PID
         height (m)    height (m)
--------------------   -----------------
BK1607     2.820    =>   2.803    SLA001
BK1609     5.730    =>   5.703    SLA002
BK1611     5.205    =>   5.130    SLA003
BK1612     5.039    =>   5.014    SLA004
BJ2124    11.685    =>  11.542    SLA005
AT0681     1.025    =>   0.999    SLA006
AU1504     2.236    =>   2.224    SLA007
AU0179     2.918    =>   2.836    SLA008
AU1505     3.020    =>   3.011    SLA009
AU0451     0.573    =>   0.612    SLA010
BH1119     0.794    =>   0.834    SLA011
BK1720     4.585    =>   4.542    SLA012
AU1507     2.451    =>   2.441    SLA013
AV0295     0.856    =>   0.692    SLA014
AU1508     1.969    =>   1.952    SLA015
AU1396     1.563    =>   1.543    SLA016
BH1094     0.893    =>   0.978    SLA017
AU1299     1.221    =>   1.204    SLA018
BJ1527     1.679    =>   1.681    SLA019
AU1300     0.625    =>   0.606    SLA020
AU0178     3.120    =>   3.037    SLA021
AU1404     1.809    =>   1.769    SLA022
AU1406     1.360    =>   1.315    SLA023
AT1395     0.697    =>   0.823    SLA024
AU1304     1.572    =>   1.548    SLA025
AU1291     1.881    =>   1.931    SLA026
AU1321     0.345    =>   0.332    SLA027
AU1307     0.763    =>   0.745    SLA028
AU1415     1.739    =>   1.696    SLA029
AU0402     3.870    =>   3.939    SLA030
AU1418     1.696    =>   1.657    SLA031
AU1309     3.096    =>   3.070    SLA032
AU1440     1.501    =>   1.474    SLA033
AU1424     3.260    =>   3.231    SLA034
AU0245     1.537    =>   1.473    SLA035
AU2085     2.645    =>   2.617    SLA036
AU2180     7.121    =>   7.186    SLA037
AU0189     2.290    =>   2.197    SLA038
AU3323    -0.470    =>  -0.426    SLA039
AU1176    -0.188    =>  -0.183    SLA040
AU2087     2.410    =>   2.383    SLA041
AT0760     0.890    =>   0.914    SLA042
AU0174     2.248    =>   2.146    SLA043
AU2089     0.858    =>   0.822    SLA044
BH1538     1.342    =>   1.377    SLA045
BH3007     0.104    =>   0.215    SLA046
AU1314     3.428    =>   3.405    SLA047
AU0272     1.869    =>   1.593    SLA048
AU2090     2.187    =>   2.158    SLA049
AU1433     2.527    =>   2.499    SLA050
AU1317     0.518    =>   0.503    SLA051
BJ2167     8.434    =>   8.332    SLA052