The presentation of physical values as control-unit-internal values and vice-versa is defined in <sw-compu-methods> (compare Conversion formulae). Differentation is made among four different conversion methods:
Polynomial presentation  The conversion is specified by six parameters (<sw-asap-6-prm-method>) (compare Example for a polynomial definition). These are separated by blanks and represent the following formula:

int = (a × x2 + b × x1 + c ) / ( d × x2 + e × x1 + f)
Table-form definition  The conversion is defined in table-form in <sw-compu-method-table> (compare Example for a conversion formula in table form). The control-unit-internal value (<cmt-int>) and the physical value (<cmt-phys>) are given for each pair of values (<sw-compu-method-value-pair>).

The type of interpolation is specified in [interpolation-style].
Text-form presentation  This conversion (<sw-compu-method-text>) represents a control-unit-internal (<cmt-int>) value in a text (<cmt-text>) (e.g. a status identifier). One <sw-compu-method-text-pair> is applied for each pair of values (compare Example for a conversion in text form).

Program code  In <prog-code>, the conversion can be specified in the notation for a programming language. Programming language ([prog-lang]), programming language dialect ([lang-subset]) and the libraries used ([used-libs]) are given as attributes.

Mathematical presentation  The conversion is specified as a general mathematical expression (<sw-compu-generic-math>). The content is open, i.e. is subject to a bilateral agreement.

Figure 15: Conversion formulae
<sw-compu-method> <long-name>decimal number in hexadecimal</long-name> <short-name>DEC</short-name> <sw-unit-ref>dechex</sw-unit-ref> <sw-asap-6-prm-method>0 1 0 0 0 1</sw-asap-6-prm-method> </sw-compu-method>
<sw-compu-method> <long-name></long-name> <short-name>LAMPTAB</short-name> <sw-unit-ref>digital</sw-unit-ref> <sw-compu-method-table> <sw-compu-method-value-pair> <cmt-int>0</cmt-int> <cmt-phys>0</cmt-phys> </cmt-compu-method-value-pair> <sw-compu-method-value-pair> <cmt-int>16</cmt-int> <cmt-phys>16</cmt-phys> </cmt-compu-method-value-pair> </sw-compu-method-table> </sw-compu-method>
<sw-compu-method> <long-name></long-name> <short-name>vkspecial</short-name> <sw-unit-ref></sw-unit-ref> <sw-compu-method-text> <sw-compu-method-text-pair> <cmt-int>0</cmt-int> <cmt-text>Heck</cmt-text> </cmt-compu-method-text-pair> <sw-compu-method-text-pair> <cmt-int>16</cmt-int> <cmt-text>16</cmt-text> </cmt-compu-method-text-pair> </sw-compu-method-text> </sw-compu-method>