XMI 2.1 with EA 12.1
<xmi:XMI xmlns:uml="
http://schema.omg.org/spec/UML/2.3" xmlns:xmi="
http://schema.omg.org/spec/XMI/2.1My xmi file has the following:
<packagedElement xmi:type="uml:Class" xmi:id="EAID_c297f8fb_aef3_bd88_35f3_6560afc31e42" name="AlvCalibrationDataTypeAlv1">
<packagedElement xmi:type="uml:Class" xmi:id="EAID_42482dca_e1b0_8621_da41_7885cd87ffb5" name="DataDefProp"/>
<packagedElement xmi:type="uml:Class" xmi:id="EAID_86a55fb0_cd88_a92a_e643_c512dd284893" name="AlvOffset"/>
<packagedElement xmi:type="uml:Class" xmi:id="EAID_d6cf1044_19f7_831e_5eae_9aabaf28892f" name="Sensitivity"/>
<packagedElement xmi:type="uml:Class" xmi:id="EAID_e39e552c_6c47_8ac1_b237_5fb0592fccc5" name="Checksum"/>
</packagedElement>
After import, the AlvCalibrationDataTypeAlv1 class has AlvOffset, Checksum, DataDefProp and Sensitivity sub-classes in this order. When I export the model as xmi again, I get
<packagedElement xmi:type="uml:Class" xmi:id="EAID_03FA9522_8E9A_4130_A3DB_7C6DB1858A62" name="AlvCalibrationDataTypeAlv1" visibility="public">
<nestedClassifier xmi:type="uml:Class" xmi:id="EAID_49799FB4_B6C9_462b_93F6_B107BC30F897" name="AlvOffset" visibility="public"/>
<nestedClassifier xmi:type="uml:Class" xmi:id="EAID_256557F3_2952_4344_B939_6416616D0670" name="Checksum" visibility="public"/>
<nestedClassifier xmi:type="uml:Class" xmi:id="EAID_BEDC37A5_B584_4550_91EC_70B76D861A86" name="DataDefProp" visibility="public"/>
<nestedClassifier xmi:type="uml:Class" xmi:id="EAID_C4693AAC_CAA7_4fab_8965_38A7BAD4FE50" name="Sensitivity" visibility="public"/>
</packagedElement>
This matches the order displayed in the Project Browser but differs from the order that were defined in the original xmi file.