Skillselect 4 digit codes are group codes. A group may have multiple 6 digit sub jobs that are related to each other.
Group 2613 is for SOFTWARE AND APPLICATIONS PROGRAMMERS
As per the group definition, Software and Applications Programmers design, develop, test, maintain and document program code in accordance with user requirements, and system and technical specifications.
Example, All these jobs fall under the group 2613:
261311 Analyst Programmer
261312 Developer Programmer
261313 Software Engineer
261314 Software Tester
261399 Software and Applications Programmers nec
ACS job codes are for exact job from the group.
Steps to be done after receiving Australia PR invitation
You get 60 days to submit the proofs that you claimed points for, in your SkillSelect EOI.
This article provides detailed explanation and the documents you need to submit: