The University and College Union will target universities' IT infrastructure and libraries in any industrial action over pay this year, say documents obtained by Times Higher Education.
Matt Waddup, national head of campaigns at the UCU, said in a memo to branches last month that details of members employed in these areas were "an absolutely vital part of the union's preparations should a dispute become necessary".
Sally Hunt, general secretary of the UCU, had earlier asked branches to supply lists of external examiners and examination timetables "as a matter of urgency".
The UCU is considering a range of tactics as it continues to threaten a ballot for industrial action over pay-negotiating machinery.
A union document, Industrial Action Tactics, notes that strike action "remains the most clean-cut and visible form of protest".
But it adds: "For a strike to have impact in the sector, it would have to be (apparently) maintained for an unfeasible length of time; second, members would have financial difficulties with anything other than a two- or three-day strike; and third, there is little chance of the UCU providing a support fund sufficient to bolster a long-term strike."
Instead, the union is considering "flexible programmes" of strikes that could take place on different days in different institutions, depending on the academic calendar. They could be implemented to "increase both publicity and employer discomfort".
Other tactics could include action taken on open days and during graduations, or two- or three-day strikes during induction week, causing "disruption and bad publicity".
Following a legal case in 2007, Spackman v London Metropolitan University, universities are entitled to withhold all of an employee's pay if he or she takes part in action short of a strike. This could include not carrying out Quality Assurance Agency-related work and refusing to attend "voluntary" functions such as degree ceremonies.
The UCU document says: "This is an area fraught with difficulty, and there is relatively little scope for the union to manoeuvre."
The Universities and Colleges Employers Association has advised that universities may withhold a day's pay for each day of action, on the basis of a 260-day working year. The union has said that withdrawal of all pay when staff were performing some duties would be "tantamount to a lockout".
The UCU originally planned to ballot for action by 31 January if "satisfactory progress" had not been made in talks with Ucea over pay machinery. The union wants a separate negotiating table to discuss the pay issues of academic and academic-related staff, rather than join non-academic campus unions around a single table for all talks.
It also rejects Ucea's preferred timetable for negotiations, which the UCU said would prevent it from taking industrial action until the summer vacation.
Union and Ucea representatives met on 29 January, and the UCU extended the ballot deadline to 6 February. A UCU spokesman said this had been extended again after meetings were disrupted by last week's snow. "Constructive dialogue and an exchange of ideas have taken place," he said. "But in the absence of an agreement, we will continue with preparations for a ballot."
A Ucea spokesman said: "Employers are disappointed if the UCU has chosen to continue with ballot preparations while still in talks. However, we will continue to engage constructively with (arbitration) processes and hope that an unnecessary dispute, which would clearly harm students, can be averted."