diff --git a/api/__init__.py b/api/__init__.py
index 42255a3..511778b 100644
--- a/api/__init__.py
+++ b/api/__init__.py
@@ -52,4 +52,11 @@ from .s16_emitters import get_emitter_schema, get_emitter, set_emitter
 from .s21_times import TIME_STATISTIC_NONE, TIME_STATISTIC_AVERAGED, TIME_STATISTIC_MINIMUM, TIME_STATISTIC_MAXIMUM, TIME_STATISTIC_RANGE
 from .s21_times import get_time_schema, get_time, set_time
 
+from .s23_options import OPTION_UNITS_CFS, OPTION_UNITS_GPM, OPTION_UNITS_MGD, OPTION_UNITS_IMGD, OPTION_UNITS_AFD, OPTION_UNITS_LPS, OPTION_UNITS_LPM, OPTION_UNITS_MLD, OPTION_UNITS_CMH, OPTION_UNITS_CMD
+from .s23_options import OPTION_HEADLOSS_HW, OPTION_HEADLOSS_DW, OPTION_HEADLOSS_CM
+from .s23_options import OPTION_UNBALANCED_STOP, OPTION_UNBALANCED_CONTINUE
+from .s23_options import OPTION_DEMAND_MODEL_DDA, OPTION_DEMAND_MODEL_PDA
+from .s23_options import OPTION_QUALITY_NONE, OPTION_QUALITY_CHEMICAL, OPTION_QUALITY_AGE, OPTION_QUALITY_TRACE
+from .s23_options import get_option_schema, get_option, set_option
+
 from .s24_coordinates import get_node_coord
diff --git a/api/command.py b/api/command.py
index c293d28..791e147 100644
--- a/api/command.py
+++ b/api/command.py
@@ -11,6 +11,7 @@ from .s11_patterns import *
 from .s12_curves import *
 from .s16_emitters import *
 from .s21_times import *
+from .s23_options import *
 
 
 def execute_add_command(name: str, cs: ChangeSet) -> ChangeSet:
@@ -61,6 +62,8 @@ def execute_update_command(name: str, cs: ChangeSet) -> ChangeSet:
         return set_emitter(name, cs)
     elif type == 'time':
         return set_time(name, cs)
+    elif type == 'option':
+        return set_option(name, cs)
 
     return ChangeSet()
 
diff --git a/api/s22_options.py b/api/s22_options.py
deleted file mode 100644
index e69de29..0000000
diff --git a/api/s23_options.py b/api/s23_options.py
new file mode 100644
index 0000000..7d04fef
--- /dev/null
+++ b/api/s23_options.py
@@ -0,0 +1,101 @@
+from .operation import *
+
+OPTION_UNITS_CFS = 'CFS'
+OPTION_UNITS_GPM = 'GPM'
+OPTION_UNITS_MGD = 'MGD'
+OPTION_UNITS_IMGD = 'IMGD'
+OPTION_UNITS_AFD = 'AFD'
+OPTION_UNITS_LPS = 'LPS'
+OPTION_UNITS_LPM = 'LPM'
+OPTION_UNITS_MLD = 'MLD'
+OPTION_UNITS_CMH = 'CMH'
+OPTION_UNITS_CMD = 'CMD'
+
+OPTION_HEADLOSS_HW = 'H-W'
+OPTION_HEADLOSS_DW = 'D-W'
+OPTION_HEADLOSS_CM = 'C-M'
+
+#OPTION_HYDRAULICS_USE = 'USE'
+#OPTION_HYDRAULICS_SAVE = 'SAVE'
+
+OPTION_UNBALANCED_STOP = 'STOP'
+OPTION_UNBALANCED_CONTINUE = 'CONTINUE'
+
+OPTION_DEMAND_MODEL_DDA = 'DDA'
+OPTION_DEMAND_MODEL_PDA = 'PDA'
+
+OPTION_QUALITY_NONE = 'NONE'
+OPTION_QUALITY_CHEMICAL = 'CHEMICAL'
+OPTION_QUALITY_AGE = 'AGE'
+OPTION_QUALITY_TRACE = 'TRACE'
+
+element_schema = {'type': 'str' , 'optional': True , 'readonly': False}
+
+def get_option_schema(name: str) -> dict[str, dict[str, Any]]:
+    return { 'UNITS'             : element_schema,
+             'HEADLOSS'          : element_schema,
+            #'HYDRAULICS'        : element_schema,
+             'VISCOSITY'         : element_schema,
+             'SPECIFIC GRAVITY'  : element_schema,
+             'TRIALS'            : element_schema,
+             'ACCURACY'          : element_schema,
+             'FLOWCHANGE'        : element_schema,
+             'HEADERROR'         : element_schema,
+             'CHECKFREQ'         : element_schema,
+             'MAXCHECK'          : element_schema,
+             'DAMPLIMIT'         : element_schema,
+             'UNBALANCED'        : element_schema,
+             'DEMAND MODEL'      : element_schema,
+             'MINIMUM PRESSURE'  : element_schema,
+             'REQUIRED PRESSURE' : element_schema,
+             'PRESSURE EXPONENT' : element_schema,
+             'PATTERN'           : element_schema,
+             'DEMAND MULTIPLIER' : element_schema,
+             'EMITTER EXPONENT'  : element_schema,
+             'QUALITY'           : element_schema,
+             'DIFFUSIVITY'       : element_schema,
+             'TOLERANCE'         : element_schema,
+            #'QUALITY'           : element_schema,
+           }
+
+
+def get_option(name: str) -> dict[str, Any]:
+    ts = read_all(name, f"select * from options")
+    d = {}
+    for e in ts:
+        d[e['key']] = str(e['value'])
+    return d
+
+
+def set_option(name: str, cs: ChangeSet) -> ChangeSet:
+    raw_old = get_option(name)
+
+    old = {}
+    new = {}
+
+    new_dict = cs.operations[0]
+    schema = get_option_schema(name)
+    for key in schema.keys():
+        if key in new_dict:
+            old[key] = str(raw_old[key])
+            new[key] = str(new_dict[key])
+
+    redo_cs = g_update_prefix | { 'type' : 'option' }
+
+    redo_sql = ''
+    for key, value in new.items():
+        if redo_sql != '':
+            redo_sql += '\n'
+        redo_sql += f"update options set value = '{value}' where key = '{key}';"
+        redo_cs |= { key: value }
+
+    undo_cs = g_update_prefix | { 'type' : 'option' }
+
+    undo_sql = ''
+    for key, value in old.items():
+        if undo_sql != '':
+            undo_sql += '\n'
+        undo_sql += f"update options set value = '{value}' where key = '{key}';"
+        undo_cs |= { key: value }
+
+    return execute_command(name, redo_sql, undo_sql, redo_cs, undo_cs)
diff --git a/test_tjnetwork.py b/test_tjnetwork.py
index c4f6c0c..c5d4b1a 100644
--- a/test_tjnetwork.py
+++ b/test_tjnetwork.py
@@ -1596,6 +1596,174 @@ class TestApi:
         self.leave(p)
 
 
+    def test_option(self):
+        p = 'test_option'
+        self.enter(p)
+
+        o = get_option(p)
+        assert o['UNITS'] == OPTION_UNITS_GPM
+        assert o['HEADLOSS'] == OPTION_HEADLOSS_HW
+        assert o['VISCOSITY'] == '1.0'
+        assert o['SPECIFIC GRAVITY'] == '1.0'
+        assert o['TRIALS'] == '40'
+        assert o['ACCURACY'] == '0.001'
+        assert o['FLOWCHANGE'] == '0'
+        assert o['HEADERROR'] == '0'
+        assert o['CHECKFREQ'] == '2'
+        assert o['MAXCHECK'] == '10'
+        assert o['DAMPLIMIT'] == '0'
+        assert o['UNBALANCED'] == OPTION_UNBALANCED_STOP
+        assert o['DEMAND MODEL'] == OPTION_DEMAND_MODEL_DDA
+        assert o['MINIMUM PRESSURE'] == '0'
+        assert o['REQUIRED PRESSURE'] == '0.1'
+        assert o['PRESSURE EXPONENT'] == '0.5'
+        assert o['PATTERN'] == '1'
+        assert o['DEMAND MULTIPLIER'] == '1.0'
+        assert o['EMITTER EXPONENT'] == '0.5'
+        assert o['QUALITY'] == OPTION_QUALITY_NONE
+        assert o['DIFFUSIVITY'] == '1.0'
+        assert o['TOLERANCE'] == '0.01'
+
+        o['UNITS'] = OPTION_UNITS_LPS
+        set_option(p, ChangeSet(o))
+
+        o = get_option(p)
+        assert o['UNITS'] == OPTION_UNITS_LPS
+        assert o['HEADLOSS'] == OPTION_HEADLOSS_HW
+        assert o['VISCOSITY'] == '1.0'
+        assert o['SPECIFIC GRAVITY'] == '1.0'
+        assert o['TRIALS'] == '40'
+        assert o['ACCURACY'] == '0.001'
+        assert o['FLOWCHANGE'] == '0'
+        assert o['HEADERROR'] == '0'
+        assert o['CHECKFREQ'] == '2'
+        assert o['MAXCHECK'] == '10'
+        assert o['DAMPLIMIT'] == '0'
+        assert o['UNBALANCED'] == OPTION_UNBALANCED_STOP
+        assert o['DEMAND MODEL'] == OPTION_DEMAND_MODEL_DDA
+        assert o['MINIMUM PRESSURE'] == '0'
+        assert o['REQUIRED PRESSURE'] == '0.1'
+        assert o['PRESSURE EXPONENT'] == '0.5'
+        assert o['PATTERN'] == '1'
+        assert o['DEMAND MULTIPLIER'] == '1.0'
+        assert o['EMITTER EXPONENT'] == '0.5'
+        assert o['QUALITY'] == OPTION_QUALITY_NONE
+        assert o['DIFFUSIVITY'] == '1.0'
+        assert o['TOLERANCE'] == '0.01'
+
+        self.leave(p)
+
+
+    def test_option_op(self):
+        p = 'test_option_op'
+        self.enter(p)
+
+        o = get_option(p)
+        assert o['UNITS'] == OPTION_UNITS_GPM
+        assert o['HEADLOSS'] == OPTION_HEADLOSS_HW
+        assert o['VISCOSITY'] == '1.0'
+        assert o['SPECIFIC GRAVITY'] == '1.0'
+        assert o['TRIALS'] == '40'
+        assert o['ACCURACY'] == '0.001'
+        assert o['FLOWCHANGE'] == '0'
+        assert o['HEADERROR'] == '0'
+        assert o['CHECKFREQ'] == '2'
+        assert o['MAXCHECK'] == '10'
+        assert o['DAMPLIMIT'] == '0'
+        assert o['UNBALANCED'] == OPTION_UNBALANCED_STOP
+        assert o['DEMAND MODEL'] == OPTION_DEMAND_MODEL_DDA
+        assert o['MINIMUM PRESSURE'] == '0'
+        assert o['REQUIRED PRESSURE'] == '0.1'
+        assert o['PRESSURE EXPONENT'] == '0.5'
+        assert o['PATTERN'] == '1'
+        assert o['DEMAND MULTIPLIER'] == '1.0'
+        assert o['EMITTER EXPONENT'] == '0.5'
+        assert o['QUALITY'] == OPTION_QUALITY_NONE
+        assert o['DIFFUSIVITY'] == '1.0'
+        assert o['TOLERANCE'] == '0.01'
+
+        o['UNITS'] = OPTION_UNITS_LPS
+        cs = set_option(p, ChangeSet(o)).operations[0]
+        assert cs['operation'] == API_UPDATE
+        assert cs['type'] == 'option'
+        assert cs['UNITS'] == OPTION_UNITS_LPS
+        assert cs['HEADLOSS'] == OPTION_HEADLOSS_HW
+        assert cs['VISCOSITY'] == '1.0'
+        assert cs['SPECIFIC GRAVITY'] == '1.0'
+        assert cs['TRIALS'] == '40'
+        assert cs['ACCURACY'] == '0.001'
+        assert cs['FLOWCHANGE'] == '0'
+        assert cs['HEADERROR'] == '0'
+        assert cs['CHECKFREQ'] == '2'
+        assert cs['MAXCHECK'] == '10'
+        assert cs['DAMPLIMIT'] == '0'
+        assert cs['UNBALANCED'] == OPTION_UNBALANCED_STOP
+        assert cs['DEMAND MODEL'] == OPTION_DEMAND_MODEL_DDA
+        assert cs['MINIMUM PRESSURE'] == '0'
+        assert cs['REQUIRED PRESSURE'] == '0.1'
+        assert cs['PRESSURE EXPONENT'] == '0.5'
+        assert cs['PATTERN'] == '1'
+        assert cs['DEMAND MULTIPLIER'] == '1.0'
+        assert cs['EMITTER EXPONENT'] == '0.5'
+        assert cs['QUALITY'] == OPTION_QUALITY_NONE
+        assert cs['DIFFUSIVITY'] == '1.0'
+        assert cs['TOLERANCE'] == '0.01'
+
+        cs = execute_undo(p).operations[0]
+        assert cs['operation'] == API_UPDATE
+        assert cs['type'] == 'option'
+        assert cs['UNITS'] == OPTION_UNITS_GPM
+        assert cs['HEADLOSS'] == OPTION_HEADLOSS_HW
+        assert cs['VISCOSITY'] == '1.0'
+        assert cs['SPECIFIC GRAVITY'] == '1.0'
+        assert cs['TRIALS'] == '40'
+        assert cs['ACCURACY'] == '0.001'
+        assert cs['FLOWCHANGE'] == '0'
+        assert cs['HEADERROR'] == '0'
+        assert cs['CHECKFREQ'] == '2'
+        assert cs['MAXCHECK'] == '10'
+        assert cs['DAMPLIMIT'] == '0'
+        assert cs['UNBALANCED'] == OPTION_UNBALANCED_STOP
+        assert cs['DEMAND MODEL'] == OPTION_DEMAND_MODEL_DDA
+        assert cs['MINIMUM PRESSURE'] == '0'
+        assert cs['REQUIRED PRESSURE'] == '0.1'
+        assert cs['PRESSURE EXPONENT'] == '0.5'
+        assert cs['PATTERN'] == '1'
+        assert cs['DEMAND MULTIPLIER'] == '1.0'
+        assert cs['EMITTER EXPONENT'] == '0.5'
+        assert cs['QUALITY'] == OPTION_QUALITY_NONE
+        assert cs['DIFFUSIVITY'] == '1.0'
+        assert cs['TOLERANCE'] == '0.01'
+
+        cs = execute_redo(p).operations[0]
+        assert cs['operation'] == API_UPDATE
+        assert cs['type'] == 'option'
+        assert cs['UNITS'] == OPTION_UNITS_LPS
+        assert cs['HEADLOSS'] == OPTION_HEADLOSS_HW
+        assert cs['VISCOSITY'] == '1.0'
+        assert cs['SPECIFIC GRAVITY'] == '1.0'
+        assert cs['TRIALS'] == '40'
+        assert cs['ACCURACY'] == '0.001'
+        assert cs['FLOWCHANGE'] == '0'
+        assert cs['HEADERROR'] == '0'
+        assert cs['CHECKFREQ'] == '2'
+        assert cs['MAXCHECK'] == '10'
+        assert cs['DAMPLIMIT'] == '0'
+        assert cs['UNBALANCED'] == OPTION_UNBALANCED_STOP
+        assert cs['DEMAND MODEL'] == OPTION_DEMAND_MODEL_DDA
+        assert cs['MINIMUM PRESSURE'] == '0'
+        assert cs['REQUIRED PRESSURE'] == '0.1'
+        assert cs['PRESSURE EXPONENT'] == '0.5'
+        assert cs['PATTERN'] == '1'
+        assert cs['DEMAND MULTIPLIER'] == '1.0'
+        assert cs['EMITTER EXPONENT'] == '0.5'
+        assert cs['QUALITY'] == OPTION_QUALITY_NONE
+        assert cs['DIFFUSIVITY'] == '1.0'
+        assert cs['TOLERANCE'] == '0.01'
+
+        self.leave(p)
+
+
     def test_snapshot(self):
         p = "test_snapshot"
         self.enter(p)
diff --git a/tjnetwork.py b/tjnetwork.py
index 33e7ff7..8c637c6 100644
--- a/tjnetwork.py
+++ b/tjnetwork.py
@@ -50,6 +50,32 @@ TIME_STATISTIC_MINIMUM = api.TIME_STATISTIC_MINIMUM
 TIME_STATISTIC_MAXIMUM = api.TIME_STATISTIC_MAXIMUM
 TIME_STATISTIC_RANGE = api.TIME_STATISTIC_RANGE
 
+OPTION_UNITS_CFS = api.OPTION_UNITS_CFS
+OPTION_UNITS_GPM = api.OPTION_UNITS_GPM
+OPTION_UNITS_MGD = api.OPTION_UNITS_MGD
+OPTION_UNITS_IMGD = api.OPTION_UNITS_IMGD
+OPTION_UNITS_AFD = api.OPTION_UNITS_AFD
+OPTION_UNITS_LPS = api.OPTION_UNITS_LPS
+OPTION_UNITS_LPM = api.OPTION_UNITS_LPM
+OPTION_UNITS_MLD = api.OPTION_UNITS_MLD
+OPTION_UNITS_CMH = api.OPTION_UNITS_CMH
+OPTION_UNITS_CMD = api.OPTION_UNITS_CMD
+
+OPTION_HEADLOSS_HW = api.OPTION_HEADLOSS_HW
+OPTION_HEADLOSS_DW = api.OPTION_HEADLOSS_DW
+OPTION_HEADLOSS_CM = api.OPTION_HEADLOSS_CM
+
+OPTION_UNBALANCED_STOP = api.OPTION_UNBALANCED_STOP
+OPTION_UNBALANCED_CONTINUE = api.OPTION_UNBALANCED_CONTINUE
+
+OPTION_DEMAND_MODEL_DDA = api.OPTION_DEMAND_MODEL_DDA
+OPTION_DEMAND_MODEL_PDA = api.OPTION_DEMAND_MODEL_PDA
+
+OPTION_QUALITY_NONE = api.OPTION_QUALITY_NONE
+OPTION_QUALITY_CHEMICAL = api.OPTION_QUALITY_CHEMICAL
+OPTION_QUALITY_AGE = api.OPTION_QUALITY_AGE
+OPTION_QUALITY_TRACE = api.OPTION_QUALITY_TRACE
+
 
 ############################################################
 # project
@@ -387,6 +413,20 @@ def set_time(name: str, cs: ChangeSet) -> ChangeSet:
     return api.set_time(name, cs)
 
 
+############################################################
+# option 23.[OPTIONS]
+############################################################
+
+def get_option_schema(name: str) -> dict[str, dict[str, Any]]:
+    return api.get_option_schema(name)
+
+def get_option(name: str) -> dict[str, Any]:
+    return api.get_option(name)
+
+def set_option(name: str, cs: ChangeSet) -> ChangeSet:
+    return api.set_option(name, cs)
+
+
 ############################################################
 # coord 24.[COORDINATES]
 ############################################################