Help TOC > Instructions for DEX developers > Developing DEX Specifications > EXPRESS long forms
EXPRESS long forms Date: 2008/02/26 10:25:17
Revision: 1.9


Each DEX is made up of a series of capabilities. Each capability will specify the subset of the ISO 10303-239 (PLCS) EXPRESS model that is required. The EXPRESS models are defined in the ARM of a STEP module. This is shown in Figure 1 below.

Figure 1 —  DEX architecture

Figure 1 —  DEX architecture

The capability specifies the EXPRESS using the <usage> element. This identifies whether an EXPRESS entity is to be included or excluded from the capability EXPRESS.

Long form files

Each DEX has two normative files that specify the long form:

The EXPRESS long form.
The XML Schema P28 long form derived from dex_lf.exp.

Long form algorithm

The DEX long form is build by pruning the long form specified in the PLCS AP module long form - ap239_product_life_cycle_support (the AP long form). The approach used is as follows:

  1. All the EXPRESS entities identified in the capabilities are copied from the AP long form and added to the DEX long form. If any entity is removed by one capability and added by another, the addition takes precedence.
  2. All of the EXPRESS types used by the identified EXPRESS entities are copied from the AP long form to the DEX long form. I.e. used in an attribute of an entity.
  3. The domains of any select type in the DEX long form are then pruned so that they only contain entities that are defined in the DEX long form.
  4. All EXPRESS functions that are required by any entity in the DEX long from is then copied from the AP long from.

Long form generation process

The process for building a long form is as follows:

  1. Display the EXPRESS code for the DEX as shown in Figure 2. This will dynamically extract the EXPRESS defined by the capabilities.

    Menu: models->EXPRESS

    Figure 2 —  EXPRESS code

    Figure 2 —  EXPRESS code

  2. Copy the complete schema and paste it to the file dex_lf.exp.
  3. Convert the dex_lf.exp to the EXPRESS XML representation. One way that this can be done is by using the Eurostep Express Parser (EEP) available from (

    c:/apps/eep/Eep.exe -t -i -w -x dex_lf.exp

    This will produce Model.XML which should be copied to dex_lf.xml

  4. Display dex_lf.xml as an XML Schema (Part 28) file and paste this to dex_lf.xsd. Menu: Development views -> dex_lf.xml as XML Schema