What is mean by minOccurs and maxOccurs in xml defenition (xsd) file

minOccurs and maxOccurs are the occurrence indicators in xml. These two will decide how many times each element in the xml can be occurred/added. minOccurs can be either 0 or 1. The default is 1. That means the xml should include at least one of that  element . If minOccurs =0 means that element can be avoid to be part of xml.
maxOccurs decide the maximum limit of the occurrence of the particular element. Default maxOccurs=1.

http://www.w3schools.com/schema/schema_complex_indicators.asp