"external purposes" is correct and can be used in written English.
You might use it when referring to a purpose which is outside of a person's internal desires or motivations, for example, "She completed the task for external purposes, not out of self-interest."
The MIT grading system for external purposes does not include modifiers.
The Association writes on its website: "The first step is for universities to master their cost structures and identify the real costs of their activities for both internal and external purposes.
The ISC report will be examined to see if its members drawn from peers and MPs from all parties will recommend any changes to the system of oversight or a change to the way in which intercept warrants are issued for internal and external purposes.
When used for external purposes it remains necessary to use both qualitative and quantitative results.
At the beginning of the workshop, presentations were made to inform one another on current, planned, and future activities for measuring and reporting "wait times" at each of the cancer agencies for both internal and external purposes.
While the results of this study can be used to improve the quality of services provided by these institutions, several CQ index dimensions should be interpreted with caution for external purposes (accountability and transparency).
It took place beyond the work/recreation cycle; it was human activity unleashed from any external purpose.
For Newman, the ideal university is a community of thinkers, engaging in intellectual pursuits not for any external purpose, but as an end in itself.
The nature of the materials and techniques used for inscriptions is closely tied to the external purpose of the record itself.
Instead it's about finding your external purpose.
'Spontaneous orders' by contrast exhibit endogenous order; they do not have an external purpose.
