Data
Format

Every data set consists of two mandatory parts: electrode definitions and arrangement definition. Subsequently the number of electrodes, their positions (x z for 2D, x y z for 3D) , the number of data and their definitions are given. Comments may be placed after the # character. After the number of data the definition for each datum can be given row-wise by the electrode numbers for the current electrodes A and B (C1 and C2) and the potential electrodes M and N (P1 and P2). They may be followed by other attributes (see list below). Standard is the apparent resistivity and optional the relative error as exemplified for a tiny dipole-dipole survey.

6 # Number of electrodes
# x z
0     0
1     0
2     0 # loose ground
3     0
4     0
5     0
6 # Number of data
#a b  m   n  rhoa
1   4   2   3  231.2 # A Wenner point
1   2   3   4  231.2 # Dipol-dipole sequence
2   3   4   5  312.8
3   4   5   6  12.1   # possibly an outlier
1   2   4   5  256.7
1   0   5   6  199.7 # Pole-dipole
1   0   5   0  246.2 # Pole-pole

The token string in the line after the number of data can be omitted for the order A B M N rhoa (error). Otherwise it is used to specify the given columns The token may be followed by a slash and a physical unit. The following tokens are allowed (case insensitive).
TokensMeaningpossible units
a c1electrode number for A (C1)
b c2electrode number for B (C2)
m p1electrode number for M (P1)
n p2electrode number for N (P2)
rhoa rho_a Raapparent resistivityOhmmeter
R Z rhoResistance/ImpedanceOhm
err error stdError/standard deviation1(default),%,Ohm
ipIP measuremRad(default),,FE,MF
ICurrentA(default),mA,uA
U VVoltageV(default),mV,uV
spself potentialV(default),mV,uV
ttopography effect1
The following sample contains voltages, currents and a percentage error.

...
6 # Number of data
# a b m n U I/mA err/%
  1   2   3   4  -0.5305165 102.2 2.4
  2   3   4   5  -0.5305165 99.9  1.4
  1   2   4   5  -0.1326291 100.1 7.6
...
Topography may be given in two ways.
1. Each electrode can be given a height value as z position (preferred by webinv).
2. Alternatively, the data may be followed by a topo list (preferred by DC2dInvRes).
...
  1   2   5   6  -0.05305165  7.5
4# Number of topo points
# x h for each topo point
0 353.2
12 357.1
19 359.9
24.5 350

Buried/borehole electrodes vs. topography

There might be confusion about using z for surface topography or buried/borehole electrodes, (DCndInvRes understands z usually as depth, wheras DCTopo reads it as topography) In order to distinguish between both we provide different tokens for the electrode list: Besides x and y used for real coordinates, h (for height) and d (for depth below surface) can be provided. So the definition is unique, furthermore it is possible to combine both. A z will still be interpreted problem-dependent.