Check all schemes for unnecessary @minOccurs, @maxOccurs and @usage

Description

In railML schemes there are elements that occur exactly one time. Thus, @minOccurs="1" and @maxOccurs="1". Since these are default values, they don't have to be given explicitly. The same applies for @use="optional" for attributes.

Background

elements... are by default mandatory (minOccurs="1" and maxOccurs="1")

attributes... are by default optional (use="optional")

Therefore, mandatory elements and optional attributes don't have to have mentioned properties.

For the following cases, properties have to be provided in the schema:

• optional elements occuring once: minOccurs="0"
• optional elements occuring up to n times: minOccurs="0" and maxOccurs="n" (with n being a positive number)
• mandatory elements occurinng up to n times: maxOccurs="n" (with n being a positive number)
• mandatory attributes: use="required"

Links

• Forum discussion:
• Christian Rahmig, 02.10.2018: [https://www.railml.org/forum/index.php?t=msg&th=609&start=0&]
• Web links:
• XSD Indicators: [https://www.w3schools.com/xml/schema_complex_indicators.asp]
• XSD Attributes: [https://www.w3schools.com/xml/schema_simple_attributes.asp]

Proposed solution

Remove in all schema files:

• minOccurs="1"
• maxOccurs="1"
• use="optional"