A survey of 219 companies by the Bureau of National Affairs has revealed that 64 percent of the firms will allow informal holiday parties. However, alcoholic beverages will not be served at 86 percent of those gatherings. Last year, the BNA survey found only 42 percent of the responding companies would allow informal parties, with 90 percent disallowing booze.

Company-sponsored Christmas parties, on company time and premises, will be held in 27 percent of the companies surveyed this year. Alcoholic beverages will be available at about half of those.

BNA also surveyed the same companies on their holiday leave practices and found that 47 percent planned to make Friday, Dec. 26, a paid holiday for their employes. Twenty-three percent of the firms will give employes the Friday after New Year's Day as a paid holiday.

Employes at 22 percent of the companies will get a holiday on Christmas Eve but will have to return to work the day after Christmas. Dec. 31 will be a holiday rather than Friday, Jan. 2, in 15 percent of the companies.

For both holiday weeks, nonunion firms are more likely to give the Friday after the major holiday, whereas unionized companies more often give the eve day or both the day before and the day after the holiday.