The best practice to model a software application in a SysML model for a system is to use a block stereotyped with «software» to represent the software application and its interfaces. A block is a modular unit that encapsulates its structure and behavior and can be connected to other blocks via ports and connectors. A stereotype is an extension of an existing metaclass that adds additional information or semantics to a model element. By using a block stereotypedwith «software», the software application can be modeled as a system component with its own properties, operations, ports, flows, etc., and can be allocated to hardware blocks or other software blocks. References: https://www.omg.org/ocsmp/ocsmp-adv-exam.htm https://www.ibm.com/docs/SSB2MU_8.2.0/com.ibm.rhp.sysml.doc/topics/rhp_c_dm_sysml_profile_features.html