Well Known Text
 
WKT Version 2
COORDINATEOPERATION["Cais da Vila do Porto depth to ZH Portugal depth (1)",VERSION["IH-Por Santa Maria"],SOURCECRS[VERTCRS["Cais da Vila do Porto depth",BASEVERTCRS["Cais da Vila do Porto height",VDATUM["Cais da Vila do Porto",ID["EPSG",1109]],ID["EPSG",6186]],DERIVINGCONVERSION["Height <> Depth Conversion",METHOD["Height Depth Reversal",ID["EPSG",1068]],ID["EPSG",7812]],CS[vertical,1,ID["EPSG",6498]],AXIS["Depth (D)",down],LENGTHUNIT["metre",1,ID["EPSG",9001]],ID["EPSG",10379]]],TARGETCRS[VERTCRS["ZH Portugal depth",VDATUM["Chart Datum Portugal ",ID["EPSG",1361]],CS[vertical,1,ID["EPSG",6498]],AXIS["Depth (D)",down],LENGTHUNIT["metre",1,ID["EPSG",9001]],ID["EPSG",10349]]],METHOD["Vertical Offset",ID["EPSG",9616]],PARAMETER["Vertical Offset",-1,LENGTHUNIT["metre",1,ID["EPSG",9001]],ID["EPSG",8603]],OPERATIONACCURACY[0],ID["EPSG",10391]]