I am not entirely sure whether or not you refer to time-dependent observations. If you refer to time-dependent observations, please find an example format below.
DEF PARID LABEL NODE X Y Z SLICE ACTIVE NAME TIME TIME2 REF_VALUE WEIGHT GROUP SYNC_TIME FUNC
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Level 0 nan 0 0 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~00002 0.1 nan 0.049978 0.246915 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~00003 0.2 nan 0.099927 0.243907 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~00004 0.5 nan 0.24955 0.235319 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~00005 1 nan 0.49827 0.222308 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~00006 2 nan 0.99342 0.200264 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~00007 5 nan 2.4634 0.154717 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~00008 10 nan 4.8624 0.112836 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~00009 20 nan 9.4763 0.074204 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~0000A 50 nan 21.961 0.038519 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~0000B 100 nan 38.925 0 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~0000C 200 nan 62.359 0 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~0000D 500 nan 90.915 0 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~0000E 1000 nan 99.081 0 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~0000F 2000 nan 99.984 0 heagp 1
hea 400 Water Level 0 40 40 0 3 1 hea-Water_Leve~0000G 10000 nan 100 0 heagp 1