Key: Legal successor and corporate names. 

- HPInc is the legal successor to EDS. Responsibility was not transferred to subsequent successor companies such as  HPES, Hewlett Packard Enterprise, DXC, etc. HPInc has responsibility for any commitments to former EDS employees.  This includes any retiree health coverage, pension, 401(k), etc. plans. (Does not depend on whether the employee's last business unit ended up in HPInc or Hewlett Packard Enterprise in the HP Breakup.)

- When EDS was acquired by HP on August 26, 2008, it was temporarily structured as a wholly-owned subsidiary called "EDS, an HP Company." Source

- On Sept. 23, 2009, Hewlett-Packard Company announced that "EDS, an HP company" would be renamed "HP Enterprise Services."  Source  The timing may have varied from country to country.

- On October 21, 2015, Hewlett-Packard Company spun off Hewlett Packard Enterprise (no hyphen; singular.) The timing may have varied from country to country.

Make sure that every company you ever worked for has your current postal address. Even if not classified by the company as a "Retiree" or if long gone from the company -- in case of class-action settlements or pension issues. Update address at former company

You may have an EDS pension. If you were employed by EDS or "EDS, an HP Company" before January 1, 2009 you may have an EDS pension that you have forgotten about. https://www.hpalumni.org/edsPension

If you received a "Potential Private Retirement Benefit Information" notice from Social Security, it is usually based on outdated information -- as indicated by the "Year Reported" date on the form included in the body of the notice. Here's how to decode it: https://www.hpalumni.org/PotentialBenefitLetter

EDS 401(k):

The HPInc Retirement Service Center (operated by Fidelity Investments) manages pension and 401(k) accounts for HPInc (formerly named Hewlett-Packard Company.) Also manages any pension or 401(k) accounts that the many Hewlett-Packard predecessor companies, such as DEC and EDS, may have had.
1-800-457-4015, M-F 7:30 AM to 11:00 PM Central Time. Outside the US, call 1-508-787-9902 collect. Fidelity website: Fidelity

Stock:

- EDS stock is no longer traded. HP paid $25.00 per share to the owners of record as of August 26, 2008. ($13.9 billion -- a 32% premium over the market price of $18.86 before announcement .NYTimes ) A check was sent to the address in the ownership records for each shareholding -- Where's my stock? If the check was uncashed, the money would have eventually been turned over to a state unclaimed property department. See HPAA's page on How to check for lost stock and dividends

- If you acquired HP stock via the EDS employee stock purchase plan. Determine cost basis and ordinary income or capital gain for each lot of shares spawned by HP since the EDS acquisition -- HPInc, Hewlett Packard Enterprise, DXC Technology, Micro Focus, Perspecta...  Details and HPAA advice for former EDS employee shareholders

Service at predecessor companies. Of HP's many predecessor companies, only HP and DEC had retiree healthcare programs. Only HP, DEC, and EDS had pension plans. Over the years, HP, DEC, and EDS set aside money in dedicated trust funds to pay for those programs. Compaq, Tandem, Autonomy, Palm, etc. did not have retiree healthcare or pensions among their benefits programs. Their employees did not have those expectations and there were no corresponding trust funds to pass on to an acquiring company. Therefore, employees of those companies do not get credit under HP's retiree healthcare or pension programs for service at the predecessor company. (Predecessor service does count for FTO.) 

Other HPInc and HPE retiree benefits...  Not always obvious: Which HP-related companies am I a retiree or former employee of? HPInc or Hewlett Packard Enterprise? Given HP's complex history of  acquisitions, divestitures, and spinoffs, the company that you are legally a former employee of may not be obvious. Before contacting one of the HP-related companies, check here: Which Company for links to official and unofficial contact information for each company.   

Report disability or a death to the company: https://www.hpalumni.org/report

Vehicle discounts. When EDS had a close relationship with GM, EDS people qualified for the GM employee discount program -- today only those receiving a GM pension qualify. See Retiree Discounts.

The Hewlett-Packard Alumni Association is operated by former employees who volunteer their time. Not officially endorsed or supported by any company. More about the HPAA