11.0 Units

Data delivered to the Office of Coast Survey must adhere to standard unit of measurement reporting.  The goal of reporting units in a standard way is to understand the units the data were recorded in and allow automated conversion/transformation from one unit to another if needed by the Office of Coast Survey or downstream users of published data products. 

 

Three different classifications of deliverables require different unit reporting standards: 

 

  • Data files that have been recorded in file formats that specify the recorded units of measurement.
  • Data products which include required metadata population.
  • Prose Reports.


For data files that have been recorded in file formats that specify the recorded units of measurement, Field Units must adhere to the manufacturer's recommendations where they exist. 

 

Where metadata is required to be populated by a Field Unit, standard units of measurement must be used. 

 

A table of standard units is included for reference.

 

Standard SI base unit prefixes may be used where appropriate.

 

For prose reports, Field Units may include units of measurement that may not be captured in the standard formats included for the required metadata population. Examples include, but are not limited to Mile Marker and Shots. 

 

Table 11.0.0 Standard Units

  1. Name
  1. Unit
  1. Unit Abbreviation
  1. See Note
  1. Reference
  1. Base Unit Prefixes Available
  1. length
  1. meter, metre
  1. m
  1. 1
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. length
  1. foot
  1. ft
  1. 1
  1. EPSG
  1. N
  1. length
  1. nautical mile
  1. NM
  1. 1
  1. EPSG
  1. N
  1. length
  1. statute mile
  1. mi
  1. 1
  1. EPSG
  1. N
  1. length
  1. US survey mile
  1. miUS
  1. 1
  1. EPSG
  1. N
  1. width, breadth
  1. meter, metre
  1. m
  1. 2
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. height, depth, altitude, elevation
  1. meter, metre
  1. m
  1. 3
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. height, depth, altitude, elevation
  1. foot
  1. ft
  1. 3
  1. EPSG
  1. N
  1. height, depth, altitude, elevation
  1. US survey foot
  1. ftUS
  1. 3
  1. EPSG
  1. N
  1. height, depth, altitude, elevation
  1. fathom
  1. f
  1. 3
  1. EPSG
  1. N
  1. thickness
  1. meter, metre
  1. m
  1. 2
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. diameter
  1. meter, metre
  1. m
  1. 2
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. radius
  1. meter, metre
  1. m
  1. 2
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. distance
  1. meter, metre
  1. m
  1. 4
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. area
  1. square meter, square metre
  1. m2
  1.  
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. volume
  1. cubic meter, cubic metre
  1. m3
  1.  
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. angular measure
  1. radians
  1. rad
  1.  
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. phase angle
  1. radians
  1. rad
  1.  
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. duration
  1. seconds
  1. s
  1. 5
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. period duration, period
  1. seconds
  1. s
  1. 6
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. duration
  1. year
  1. none
  1.  
  1. EPSG
  1.  
  1. velocity
  1. meters per second, metres per second
  1. m s-1
  1.  
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. frequency
  1. hertz
  1. Hz
  1.  
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. wavelength
  1. meter, metre
  1. m
  1.  
  1. ISO 80000-3:2019. EPSG
  1. Y
  1. mass
  1. kilograms
  1. kg
  1.  
  1. ISO 80000-4:2019. EPSG
  1. Y
  1. temperature
  1. Celsius
  1. °C
  1. 7
  1. ISO 80000-5:2019. EPSG
  1. N
  1. underwater acoustic levels
  1. decibel
  1. dB
  1.  
  1. ISO 18405:2017
  1. Y

Notes

1 Length does not need to be measured along a straight line.

2 Quantity is non-negative.

3 Quantity is usually signed. The sign expresses the position of the particular point with respect to the reference line or surface and is chosen by convention.

4 A metric space might be curved. An example of a curved metric space is the surface of the earth.

5 Duration is often called time.

6 A periodic event is an event that occurs regularly with a fixed time interval.

7 The symbol °C for the degree Celsius must be preceded by a space.

 

11.1 Precision

Data delivered to the Office of Coast Survey must adhere to standard measures of precision when reporting values. The table below presents the required minimum and maximum values for reported precision for data delivered to the Office of Coast Survey. 

 

Table 11.1.0 Required Minimum and Maximum Precision 

  1. Name
  1. Minimum
  1. Maximum
  1. Decimal degrees
  1. 6 decimal places
  1. none
  1. Degrees, decimal minutes
  1. 4 decimal places
  1. none
  1. Degree, minutes, seconds
  1. 2 decimal places
  1. none
  1. Projected coordinates
  1. 1 decimal place
  1. none
  1. Height/Depth/Altitude/Elevation
  1. 2 decimal places
  1. 2 decimal places
  1. Uncertainty
  1. 2 decimal places
  1. 2 decimal places